example of a conclusion in a research

How to Write a Conclusion for Research Papers (with Examples)

The conclusion of a research paper is a crucial section that plays a significant role in the overall impact and effectiveness of your research paper. However, this is also the section that typically receives less attention compared to the introduction and the body of the paper. The conclusion serves to provide a concise summary of the key findings, their significance, their implications, and a sense of closure to the study. Discussing how can the findings be applied in real-world scenarios or inform policy, practice, or decision-making is especially valuable to practitioners and policymakers. The research paper conclusion also provides researchers with clear insights and valuable information for their own work, which they can then build on and contribute to the advancement of knowledge in the field.

The research paper conclusion should explain the significance of your findings within the broader context of your field. It restates how your results contribute to the existing body of knowledge and whether they confirm or challenge existing theories or hypotheses. Also, by identifying unanswered questions or areas requiring further investigation, your awareness of the broader research landscape can be demonstrated.

Remember to tailor the research paper conclusion to the specific needs and interests of your intended audience, which may include researchers, practitioners, policymakers, or a combination of these.

Table of Contents

What is a conclusion in a research paper, summarizing conclusion, editorial conclusion, externalizing conclusion, importance of a good research paper conclusion, how to write a conclusion for your research paper, research paper conclusion examples.

• How to write a research paper conclusion with Paperpal? 

Frequently Asked Questions

A conclusion in a research paper is the final section where you summarize and wrap up your research, presenting the key findings and insights derived from your study. The research paper conclusion is not the place to introduce new information or data that was not discussed in the main body of the paper. When working on how to conclude a research paper, remember to stick to summarizing and interpreting existing content. The research paper conclusion serves the following purposes: 1

• Warn readers of the possible consequences of not attending to the problem.
• Recommend specific course(s) of action.
• Restate key ideas to drive home the ultimate point of your research paper.
• Provide a “take-home” message that you want the readers to remember about your study.

Types of conclusions for research papers

In research papers, the conclusion provides closure to the reader. The type of research paper conclusion you choose depends on the nature of your study, your goals, and your target audience. I provide you with three common types of conclusions:

A summarizing conclusion is the most common type of conclusion in research papers. It involves summarizing the main points, reiterating the research question, and restating the significance of the findings. This common type of research paper conclusion is used across different disciplines.

An editorial conclusion is less common but can be used in research papers that are focused on proposing or advocating for a particular viewpoint or policy. It involves presenting a strong editorial or opinion based on the research findings and offering recommendations or calls to action.

An externalizing conclusion is a type of conclusion that extends the research beyond the scope of the paper by suggesting potential future research directions or discussing the broader implications of the findings. This type of conclusion is often used in more theoretical or exploratory research papers.

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The conclusion in a research paper serves several important purposes:

• Offers Implications and Recommendations : Your research paper conclusion is an excellent place to discuss the broader implications of your research and suggest potential areas for further study. It’s also an opportunity to offer practical recommendations based on your findings.
• Provides Closure : A good research paper conclusion provides a sense of closure to your paper. It should leave the reader with a feeling that they have reached the end of a well-structured and thought-provoking research project.
• Leaves a Lasting Impression : Writing a well-crafted research paper conclusion leaves a lasting impression on your readers. It’s your final opportunity to leave them with a new idea, a call to action, or a memorable quote.

Writing a strong conclusion for your research paper is essential to leave a lasting impression on your readers. Here’s a step-by-step process to help you create and know what to put in the conclusion of a research paper: 2

• Research Statement : Begin your research paper conclusion by restating your research statement. This reminds the reader of the main point you’ve been trying to prove throughout your paper. Keep it concise and clear.
• Key Points : Summarize the main arguments and key points you’ve made in your paper. Avoid introducing new information in the research paper conclusion. Instead, provide a concise overview of what you’ve discussed in the body of your paper.
• Address the Research Questions : If your research paper is based on specific research questions or hypotheses, briefly address whether you’ve answered them or achieved your research goals. Discuss the significance of your findings in this context.
• Significance : Highlight the importance of your research and its relevance in the broader context. Explain why your findings matter and how they contribute to the existing knowledge in your field.
• Implications : Explore the practical or theoretical implications of your research. How might your findings impact future research, policy, or real-world applications? Consider the “so what?” question.
• Future Research : Offer suggestions for future research in your area. What questions or aspects remain unanswered or warrant further investigation? This shows that your work opens the door for future exploration.
• Closing Thought : Conclude your research paper conclusion with a thought-provoking or memorable statement. This can leave a lasting impression on your readers and wrap up your paper effectively. Avoid introducing new information or arguments here.
• Proofread and Revise : Carefully proofread your conclusion for grammar, spelling, and clarity. Ensure that your ideas flow smoothly and that your conclusion is coherent and well-structured.

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Remember that a well-crafted research paper conclusion is a reflection of the strength of your research and your ability to communicate its significance effectively. It should leave a lasting impression on your readers and tie together all the threads of your paper. Now you know how to start the conclusion of a research paper and what elements to include to make it impactful, let’s look at a research paper conclusion sample.

How to write a research paper conclusion with Paperpal?

A research paper conclusion is not just a summary of your study, but a synthesis of the key findings that ties the research together and places it in a broader context. A research paper conclusion should be concise, typically around one paragraph in length. However, some complex topics may require a longer conclusion to ensure the reader is left with a clear understanding of the study’s significance. Paperpal, an AI writing assistant trusted by over 800,000 academics globally, can help you write a well-structured conclusion for your research paper. 

• Sign Up or Log In: Create a new Paperpal account or login with your details.  
• Navigate to Features : Once logged in, head over to the features’ side navigation pane. Click on Templates and you’ll find a suite of generative AI features to help you write better, faster.  
• Generate an outline: Under Templates, select ‘Outlines’. Choose ‘Research article’ as your document type.  
• Select your section: Since you’re focusing on the conclusion, select this section when prompted.  
• Choose your field of study: Identifying your field of study allows Paperpal to provide more targeted suggestions, ensuring the relevance of your conclusion to your specific area of research. 
• Provide a brief description of your study: Enter details about your research topic and findings. This information helps Paperpal generate a tailored outline that aligns with your paper’s content. 
• Generate the conclusion outline: After entering all necessary details, click on ‘generate’. Paperpal will then create a structured outline for your conclusion, to help you start writing and build upon the outline.  
• Write your conclusion: Use the generated outline to build your conclusion. The outline serves as a guide, ensuring you cover all critical aspects of a strong conclusion, from summarizing key findings to highlighting the research’s implications. 
• Refine and enhance: Paperpal’s ‘Make Academic’ feature can be particularly useful in the final stages. Select any paragraph of your conclusion and use this feature to elevate the academic tone, ensuring your writing is aligned to the academic journal standards. 

By following these steps, Paperpal not only simplifies the process of writing a research paper conclusion but also ensures it is impactful, concise, and aligned with academic standards. Sign up with Paperpal today and write your research paper conclusion 2x faster .  

The research paper conclusion is a crucial part of your paper as it provides the final opportunity to leave a strong impression on your readers. In the research paper conclusion, summarize the main points of your research paper by restating your research statement, highlighting the most important findings, addressing the research questions or objectives, explaining the broader context of the study, discussing the significance of your findings, providing recommendations if applicable, and emphasizing the takeaway message. The main purpose of the conclusion is to remind the reader of the main point or argument of your paper and to provide a clear and concise summary of the key findings and their implications. All these elements should feature on your list of what to put in the conclusion of a research paper to create a strong final statement for your work.

A strong conclusion is a critical component of a research paper, as it provides an opportunity to wrap up your arguments, reiterate your main points, and leave a lasting impression on your readers. Here are the key elements of a strong research paper conclusion: 1. Conciseness : A research paper conclusion should be concise and to the point. It should not introduce new information or ideas that were not discussed in the body of the paper. 2. Summarization : The research paper conclusion should be comprehensive enough to give the reader a clear understanding of the research’s main contributions. 3 . Relevance : Ensure that the information included in the research paper conclusion is directly relevant to the research paper’s main topic and objectives; avoid unnecessary details. 4 . Connection to the Introduction : A well-structured research paper conclusion often revisits the key points made in the introduction and shows how the research has addressed the initial questions or objectives. 5. Emphasis : Highlight the significance and implications of your research. Why is your study important? What are the broader implications or applications of your findings? 6 . Call to Action : Include a call to action or a recommendation for future research or action based on your findings.

The length of a research paper conclusion can vary depending on several factors, including the overall length of the paper, the complexity of the research, and the specific journal requirements. While there is no strict rule for the length of a conclusion, but it’s generally advisable to keep it relatively short. A typical research paper conclusion might be around 5-10% of the paper’s total length. For example, if your paper is 10 pages long, the conclusion might be roughly half a page to one page in length.

In general, you do not need to include citations in the research paper conclusion. Citations are typically reserved for the body of the paper to support your arguments and provide evidence for your claims. However, there may be some exceptions to this rule: 1. If you are drawing a direct quote or paraphrasing a specific source in your research paper conclusion, you should include a citation to give proper credit to the original author. 2. If your conclusion refers to or discusses specific research, data, or sources that are crucial to the overall argument, citations can be included to reinforce your conclusion’s validity.

The conclusion of a research paper serves several important purposes: 1. Summarize the Key Points 2. Reinforce the Main Argument 3. Provide Closure 4. Offer Insights or Implications 5. Engage the Reader. 6. Reflect on Limitations

Remember that the primary purpose of the research paper conclusion is to leave a lasting impression on the reader, reinforcing the key points and providing closure to your research. It’s often the last part of the paper that the reader will see, so it should be strong and well-crafted.

• Makar, G., Foltz, C., Lendner, M., & Vaccaro, A. R. (2018). How to write effective discussion and conclusion sections. Clinical spine surgery, 31(8), 345-346.
• Bunton, D. (2005). The structure of PhD conclusion chapters.  Journal of English for academic purposes ,  4 (3), 207-224.

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Home » Research Paper Conclusion – Writing Guide and Examples

Research Paper Conclusion – Writing Guide and Examples

Table of Contents

Research Paper Conclusion

Definition:

A research paper conclusion is the final section of a research paper that summarizes the key findings, significance, and implications of the research. It is the writer’s opportunity to synthesize the information presented in the paper, draw conclusions, and make recommendations for future research or actions.

The conclusion should provide a clear and concise summary of the research paper, reiterating the research question or problem, the main results, and the significance of the findings. It should also discuss the limitations of the study and suggest areas for further research.

Parts of Research Paper Conclusion

The parts of a research paper conclusion typically include:

Restatement of the Thesis

The conclusion should begin by restating the thesis statement from the introduction in a different way. This helps to remind the reader of the main argument or purpose of the research.

Summary of Key Findings

The conclusion should summarize the main findings of the research, highlighting the most important results and conclusions. This section should be brief and to the point.

Implications and Significance

In this section, the researcher should explain the implications and significance of the research findings. This may include discussing the potential impact on the field or industry, highlighting new insights or knowledge gained, or pointing out areas for future research.

Limitations and Recommendations

It is important to acknowledge any limitations or weaknesses of the research and to make recommendations for how these could be addressed in future studies. This shows that the researcher is aware of the potential limitations of their work and is committed to improving the quality of research in their field.

Concluding Statement

The conclusion should end with a strong concluding statement that leaves a lasting impression on the reader. This could be a call to action, a recommendation for further research, or a final thought on the topic.

How to Write Research Paper Conclusion

Here are some steps you can follow to write an effective research paper conclusion:

• Restate the research problem or question: Begin by restating the research problem or question that you aimed to answer in your research. This will remind the reader of the purpose of your study.
• Summarize the main points: Summarize the key findings and results of your research. This can be done by highlighting the most important aspects of your research and the evidence that supports them.
• Discuss the implications: Discuss the implications of your findings for the research area and any potential applications of your research. You should also mention any limitations of your research that may affect the interpretation of your findings.
• Provide a conclusion : Provide a concise conclusion that summarizes the main points of your paper and emphasizes the significance of your research. This should be a strong and clear statement that leaves a lasting impression on the reader.
• Offer suggestions for future research: Lastly, offer suggestions for future research that could build on your findings and contribute to further advancements in the field.

Remember that the conclusion should be brief and to the point, while still effectively summarizing the key findings and implications of your research.

Example of Research Paper Conclusion

Here’s an example of a research paper conclusion:

Conclusion :

In conclusion, our study aimed to investigate the relationship between social media use and mental health among college students. Our findings suggest that there is a significant association between social media use and increased levels of anxiety and depression among college students. This highlights the need for increased awareness and education about the potential negative effects of social media use on mental health, particularly among college students.

Despite the limitations of our study, such as the small sample size and self-reported data, our findings have important implications for future research and practice. Future studies should aim to replicate our findings in larger, more diverse samples, and investigate the potential mechanisms underlying the association between social media use and mental health. In addition, interventions should be developed to promote healthy social media use among college students, such as mindfulness-based approaches and social media detox programs.

Overall, our study contributes to the growing body of research on the impact of social media on mental health, and highlights the importance of addressing this issue in the context of higher education. By raising awareness and promoting healthy social media use among college students, we can help to reduce the negative impact of social media on mental health and improve the well-being of young adults.

Purpose of Research Paper Conclusion

The purpose of a research paper conclusion is to provide a summary and synthesis of the key findings, significance, and implications of the research presented in the paper. The conclusion serves as the final opportunity for the writer to convey their message and leave a lasting impression on the reader.

The conclusion should restate the research problem or question, summarize the main results of the research, and explain their significance. It should also acknowledge the limitations of the study and suggest areas for future research or action.

Overall, the purpose of the conclusion is to provide a sense of closure to the research paper and to emphasize the importance of the research and its potential impact. It should leave the reader with a clear understanding of the main findings and why they matter. The conclusion serves as the writer’s opportunity to showcase their contribution to the field and to inspire further research and action.

When to Write Research Paper Conclusion

The conclusion of a research paper should be written after the body of the paper has been completed. It should not be written until the writer has thoroughly analyzed and interpreted their findings and has written a complete and cohesive discussion of the research.

Before writing the conclusion, the writer should review their research paper and consider the key points that they want to convey to the reader. They should also review the research question, hypotheses, and methodology to ensure that they have addressed all of the necessary components of the research.

Once the writer has a clear understanding of the main findings and their significance, they can begin writing the conclusion. The conclusion should be written in a clear and concise manner, and should reiterate the main points of the research while also providing insights and recommendations for future research or action.

Characteristics of Research Paper Conclusion

The characteristics of a research paper conclusion include:

• Clear and concise: The conclusion should be written in a clear and concise manner, summarizing the key findings and their significance.
• Comprehensive: The conclusion should address all of the main points of the research paper, including the research question or problem, the methodology, the main results, and their implications.
• Future-oriented : The conclusion should provide insights and recommendations for future research or action, based on the findings of the research.
• Impressive : The conclusion should leave a lasting impression on the reader, emphasizing the importance of the research and its potential impact.
• Objective : The conclusion should be based on the evidence presented in the research paper, and should avoid personal biases or opinions.
• Unique : The conclusion should be unique to the research paper and should not simply repeat information from the introduction or body of the paper.

Advantages of Research Paper Conclusion

The advantages of a research paper conclusion include:

• Summarizing the key findings : The conclusion provides a summary of the main findings of the research, making it easier for the reader to understand the key points of the study.
• Emphasizing the significance of the research: The conclusion emphasizes the importance of the research and its potential impact, making it more likely that readers will take the research seriously and consider its implications.
• Providing recommendations for future research or action : The conclusion suggests practical recommendations for future research or action, based on the findings of the study.
• Providing closure to the research paper : The conclusion provides a sense of closure to the research paper, tying together the different sections of the paper and leaving a lasting impression on the reader.
• Demonstrating the writer’s contribution to the field : The conclusion provides the writer with an opportunity to showcase their contribution to the field and to inspire further research and action.

Limitations of Research Paper Conclusion

While the conclusion of a research paper has many advantages, it also has some limitations that should be considered, including:

• I nability to address all aspects of the research: Due to the limited space available in the conclusion, it may not be possible to address all aspects of the research in detail.
• Subjectivity : While the conclusion should be objective, it may be influenced by the writer’s personal biases or opinions.
• Lack of new information: The conclusion should not introduce new information that has not been discussed in the body of the research paper.
• Lack of generalizability: The conclusions drawn from the research may not be applicable to other contexts or populations, limiting the generalizability of the study.
• Misinterpretation by the reader: The reader may misinterpret the conclusions drawn from the research, leading to a misunderstanding of the findings.

About the author

Muhammad Hassan

Researcher, Academic Writer, Web developer

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• How to Write Discussions and Conclusions

The discussion section contains the results and outcomes of a study. An effective discussion informs readers what can be learned from your experiment and provides context for the results.

What makes an effective discussion?

When you’re ready to write your discussion, you’ve already introduced the purpose of your study and provided an in-depth description of the methodology. The discussion informs readers about the larger implications of your study based on the results. Highlighting these implications while not overstating the findings can be challenging, especially when you’re submitting to a journal that selects articles based on novelty or potential impact. Regardless of what journal you are submitting to, the discussion section always serves the same purpose: concluding what your study results actually mean.

A successful discussion section puts your findings in context. It should include:

• the results of your research,
• a discussion of related research, and
• a comparison between your results and initial hypothesis.

Tip: Not all journals share the same naming conventions.

You can apply the advice in this article to the conclusion, results or discussion sections of your manuscript.

Our Early Career Researcher community tells us that the conclusion is often considered the most difficult aspect of a manuscript to write. To help, this guide provides questions to ask yourself, a basic structure to model your discussion off of and examples from published manuscripts. 

Questions to ask yourself:

• Was my hypothesis correct?
• If my hypothesis is partially correct or entirely different, what can be learned from the results? 
• How do the conclusions reshape or add onto the existing knowledge in the field? What does previous research say about the topic? 
• Why are the results important or relevant to your audience? Do they add further evidence to a scientific consensus or disprove prior studies? 
• How can future research build on these observations? What are the key experiments that must be done? 
• What is the “take-home” message you want your reader to leave with?

How to structure a discussion

Trying to fit a complete discussion into a single paragraph can add unnecessary stress to the writing process. If possible, you’ll want to give yourself two or three paragraphs to give the reader a comprehensive understanding of your study as a whole. Here’s one way to structure an effective discussion:

Writing Tips

While the above sections can help you brainstorm and structure your discussion, there are many common mistakes that writers revert to when having difficulties with their paper. Writing a discussion can be a delicate balance between summarizing your results, providing proper context for your research and avoiding introducing new information. Remember that your paper should be both confident and honest about the results! 

• Read the journal’s guidelines on the discussion and conclusion sections. If possible, learn about the guidelines before writing the discussion to ensure you’re writing to meet their expectations. 
• Begin with a clear statement of the principal findings. This will reinforce the main take-away for the reader and set up the rest of the discussion. 
• Explain why the outcomes of your study are important to the reader. Discuss the implications of your findings realistically based on previous literature, highlighting both the strengths and limitations of the research. 
• State whether the results prove or disprove your hypothesis. If your hypothesis was disproved, what might be the reasons? 
• Introduce new or expanded ways to think about the research question. Indicate what next steps can be taken to further pursue any unresolved questions. 
• If dealing with a contemporary or ongoing problem, such as climate change, discuss possible consequences if the problem is avoided. 
• Be concise. Adding unnecessary detail can distract from the main findings. 

Don’t

• Rewrite your abstract. Statements with “we investigated” or “we studied” generally do not belong in the discussion. 
• Include new arguments or evidence not previously discussed. Necessary information and evidence should be introduced in the main body of the paper. 
• Apologize. Even if your research contains significant limitations, don’t undermine your authority by including statements that doubt your methodology or execution. 
• Shy away from speaking on limitations or negative results. Including limitations and negative results will give readers a complete understanding of the presented research. Potential limitations include sources of potential bias, threats to internal or external validity, barriers to implementing an intervention and other issues inherent to the study design. 
• Overstate the importance of your findings. Making grand statements about how a study will fully resolve large questions can lead readers to doubt the success of the research. 

Snippets of Effective Discussions:

Consumer-based actions to reduce plastic pollution in rivers: A multi-criteria decision analysis approach

Identifying reliable indicators of fitness in polar bears

• How to Write a Great Title
• How to Write an Abstract
• How to Write Your Methods
• How to Report Statistics
• How to Edit Your Work

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How to write a strong conclusion for your research paper

Last updated

17 February 2024

Reviewed by

Writing a research paper is a chance to share your knowledge and hypothesis. It's an opportunity to demonstrate your many hours of research and prove your ability to write convincingly.

Ideally, by the end of your research paper, you'll have brought your readers on a journey to reach the conclusions you've pre-determined. However, if you don't stick the landing with a good conclusion, you'll risk losing your reader’s trust.

Writing a strong conclusion for your research paper involves a few important steps, including restating the thesis and summing up everything properly.

Find out what to include and what to avoid, so you can effectively demonstrate your understanding of the topic and prove your expertise.

• Why is a good conclusion important?

A good conclusion can cement your paper in the reader’s mind. Making a strong impression in your introduction can draw your readers in, but it's the conclusion that will inspire them.

• What to include in a research paper conclusion

There are a few specifics you should include in your research paper conclusion. Offer your readers some sense of urgency or consequence by pointing out why they should care about the topic you have covered. Discuss any common problems associated with your topic and provide suggestions as to how these problems can be solved or addressed.

The conclusion should include a restatement of your initial thesis. Thesis statements are strengthened after you’ve presented supporting evidence (as you will have done in the paper), so make a point to reintroduce it at the end.

Finally, recap the main points of your research paper, highlighting the key takeaways you want readers to remember. If you've made multiple points throughout the paper, refer to the ones with the strongest supporting evidence.

• Steps for writing a research paper conclusion

Many writers find the conclusion the most challenging part of any research project . By following these three steps, you'll be prepared to write a conclusion that is effective and concise.

• Step 1: Restate the problem

Always begin by restating the research problem in the conclusion of a research paper. This serves to remind the reader of your hypothesis and refresh them on the main point of the paper. 

When restating the problem, take care to avoid using exactly the same words you employed earlier in the paper.

• Step 2: Sum up the paper

After you've restated the problem, sum up the paper by revealing your overall findings. The method for this differs slightly, depending on whether you're crafting an argumentative paper or an empirical paper.

Argumentative paper: Restate your thesis and arguments

Argumentative papers involve introducing a thesis statement early on. In crafting the conclusion for an argumentative paper, always restate the thesis, outlining the way you've developed it throughout the entire paper.

It might be appropriate to mention any counterarguments in the conclusion, so you can demonstrate how your thesis is correct or how the data best supports your main points.

Empirical paper: Summarize research findings

Empirical papers break down a series of research questions. In your conclusion, discuss the findings your research revealed, including any information that surprised you.

Be clear about the conclusions you reached, and explain whether or not you expected to arrive at these particular ones.

• Step 3: Discuss the implications of your research

Argumentative papers and empirical papers also differ in this part of a research paper conclusion. Here are some tips on crafting conclusions for argumentative and empirical papers.

Argumentative paper: Powerful closing statement

In an argumentative paper, you'll have spent a great deal of time expressing the opinions you formed after doing a significant amount of research. Make a strong closing statement in your argumentative paper's conclusion to share the significance of your work.

You can outline the next steps through a bold call to action, or restate how powerful your ideas turned out to be.

Empirical paper: Directions for future research

Empirical papers are broader in scope. They usually cover a variety of aspects and can include several points of view.

To write a good conclusion for an empirical paper, suggest the type of research that could be done in the future, including methods for further investigation or outlining ways other researchers might proceed.

If you feel your research had any limitations, even if they were outside your control, you could mention these in your conclusion.

After you finish outlining your conclusion, ask someone to read it and offer feedback. In any research project you're especially close to, it can be hard to identify problem areas. Having a close friend or someone whose opinion you value read the research paper and provide honest feedback can be invaluable. Take note of any suggested edits and consider incorporating them into your paper if they make sense.

• Things to avoid in a research paper conclusion

Keep these aspects to avoid in mind as you're writing your conclusion and refer to them after you've created an outline.

Dry summary

Writing a memorable, succinct conclusion is arguably more important than a strong introduction. Take care to avoid just rephrasing your main points, and don't fall into the trap of repeating dry facts or citations.

You can provide a new perspective for your readers to think about or contextualize your research. Either way, make the conclusion vibrant and interesting, rather than a rote recitation of your research paper’s highlights.

Clichéd or generic phrasing

Your research paper conclusion should feel fresh and inspiring. Avoid generic phrases like "to sum up" or "in conclusion." These phrases tend to be overused, especially in an academic context and might turn your readers off.

The conclusion also isn't the time to introduce colloquial phrases or informal language. Retain a professional, confident tone consistent throughout your paper’s conclusion so it feels exciting and bold.

New data or evidence

While you should present strong data throughout your paper, the conclusion isn't the place to introduce new evidence. This is because readers are engaged in actively learning as they read through the body of your paper.

By the time they reach the conclusion, they will have formed an opinion one way or the other (hopefully in your favor!). Introducing new evidence in the conclusion will only serve to surprise or frustrate your reader.

Ignoring contradictory evidence

If your research reveals contradictory evidence, don't ignore it in the conclusion. This will damage your credibility as an expert and might even serve to highlight the contradictions.

Be as transparent as possible and admit to any shortcomings in your research, but don't dwell on them for too long.

Ambiguous or unclear resolutions

The point of a research paper conclusion is to provide closure and bring all your ideas together. You should wrap up any arguments you introduced in the paper and tie up any loose ends, while demonstrating why your research and data are strong.

Use direct language in your conclusion and avoid ambiguity. Even if some of the data and sources you cite are inconclusive or contradictory, note this in your conclusion to come across as confident and trustworthy.

• Examples of research paper conclusions

Your research paper should provide a compelling close to the paper as a whole, highlighting your research and hard work. While the conclusion should represent your unique style, these examples offer a starting point:

Ultimately, the data we examined all point to the same conclusion: Encouraging a good work-life balance improves employee productivity and benefits the company overall. The research suggests that when employees feel their personal lives are valued and respected by their employers, they are more likely to be productive when at work. In addition, company turnover tends to be reduced when employees have a balance between their personal and professional lives. While additional research is required to establish ways companies can support employees in creating a stronger work-life balance, it's clear the need is there.

Social media is a primary method of communication among young people. As we've seen in the data presented, most young people in high school use a variety of social media applications at least every hour, including Instagram and Facebook. While social media is an avenue for connection with peers, research increasingly suggests that social media use correlates with body image issues. Young girls with lower self-esteem tend to use social media more often than those who don't log onto social media apps every day. As new applications continue to gain popularity, and as more high school students are given smartphones, more research will be required to measure the effects of prolonged social media use.

What are the different kinds of research paper conclusions?

There are no formal types of research paper conclusions. Ultimately, the conclusion depends on the outline of your paper and the type of research you’re presenting. While some experts note that research papers can end with a new perspective or commentary, most papers should conclude with a combination of both. The most important aspect of a good research paper conclusion is that it accurately represents the body of the paper.

Can I present new arguments in my research paper conclusion?

Research paper conclusions are not the place to introduce new data or arguments. The body of your paper is where you should share research and insights, where the reader is actively absorbing the content. By the time a reader reaches the conclusion of the research paper, they should have formed their opinion. Introducing new arguments in the conclusion can take a reader by surprise, and not in a positive way. It might also serve to frustrate readers.

How long should a research paper conclusion be?

There's no set length for a research paper conclusion. However, it's a good idea not to run on too long, since conclusions are supposed to be succinct. A good rule of thumb is to keep your conclusion around 5 to 10 percent of the paper's total length. If your paper is 10 pages, try to keep your conclusion under one page.

What should I include in a research paper conclusion?

A good research paper conclusion should always include a sense of urgency, so the reader can see how and why the topic should matter to them. You can also note some recommended actions to help fix the problem and some obstacles they might encounter. A conclusion should also remind the reader of the thesis statement, along with the main points you covered in the paper. At the end of the conclusion, add a powerful closing statement that helps cement the paper in the mind of the reader.

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In a short paper—even a research paper—you don’t need to provide an exhaustive summary as part of your conclusion. But you do need to make some kind of transition between your final body paragraph and your concluding paragraph. This may come in the form of a few sentences of summary. Or it may come in the form of a sentence that brings your readers back to your thesis or main idea and reminds your readers where you began and how far you have traveled.

So, for example, in a paper about the relationship between ADHD and rejection sensitivity, Vanessa Roser begins by introducing readers to the fact that researchers have studied the relationship between the two conditions and then provides her explanation of that relationship. Here’s her thesis: “While socialization may indeed be an important factor in RS, I argue that individuals with ADHD may also possess a neurological predisposition to RS that is exacerbated by the differing executive and emotional regulation characteristic of ADHD.”

In her final paragraph, Roser reminds us of where she started by echoing her thesis: “This literature demonstrates that, as with many other conditions, ADHD and RS share a delicately intertwined pattern of neurological similarities that is rooted in the innate biology of an individual’s mind, a connection that cannot be explained in full by the behavioral mediation hypothesis.”  

Highlight the “so what”  

At the beginning of your paper, you explain to your readers what’s at stake—why they should care about the argument you’re making. In your conclusion, you can bring readers back to those stakes by reminding them why your argument is important in the first place. You can also draft a few sentences that put those stakes into a new or broader context.

In the conclusion to her paper about ADHD and RS, Roser echoes the stakes she established in her introduction—that research into connections between ADHD and RS has led to contradictory results, raising questions about the “behavioral mediation hypothesis.”

She writes, “as with many other conditions, ADHD and RS share a delicately intertwined pattern of neurological similarities that is rooted in the innate biology of an individual’s mind, a connection that cannot be explained in full by the behavioral mediation hypothesis.”  

Leave your readers with the “now what”  

After the “what” and the “so what,” you should leave your reader with some final thoughts. If you have written a strong introduction, your readers will know why you have been arguing what you have been arguing—and why they should care. And if you’ve made a good case for your thesis, then your readers should be in a position to see things in a new way, understand new questions, or be ready for something that they weren’t ready for before they read your paper.

In her conclusion, Roser offers two “now what” statements. First, she explains that it is important to recognize that the flawed behavioral mediation hypothesis “seems to place a degree of fault on the individual. It implies that individuals with ADHD must have elicited such frequent or intense rejection by virtue of their inadequate social skills, erasing the possibility that they may simply possess a natural sensitivity to emotion.” She then highlights the broader implications for treatment of people with ADHD, noting that recognizing the actual connection between rejection sensitivity and ADHD “has profound implications for understanding how individuals with ADHD might best be treated in educational settings, by counselors, family, peers, or even society as a whole.”

To find your own “now what” for your essay’s conclusion, try asking yourself these questions:

• What can my readers now understand, see in a new light, or grapple with that they would not have understood in the same way before reading my paper? Are we a step closer to understanding a larger phenomenon or to understanding why what was at stake is so important?  
• What questions can I now raise that would not have made sense at the beginning of my paper? Questions for further research? Other ways that this topic could be approached?  
• Are there other applications for my research? Could my questions be asked about different data in a different context? Could I use my methods to answer a different question?  
• What action should be taken in light of this argument? What action do I predict will be taken or could lead to a solution?  
• What larger context might my argument be a part of?  

What to avoid in your conclusion  

• a complete restatement of all that you have said in your paper.  
• a substantial counterargument that you do not have space to refute; you should introduce counterarguments before your conclusion.  
• an apology for what you have not said. If you need to explain the scope of your paper, you should do this sooner—but don’t apologize for what you have not discussed in your paper.  
• fake transitions like “in conclusion” that are followed by sentences that aren’t actually conclusions. (“In conclusion, I have now demonstrated that my thesis is correct.”)
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The conclusion is intended to help the reader understand why your research should matter to them after they have finished reading the paper. A conclusion is not merely a summary of the main topics covered or a re-statement of your research problem, but a synthesis of key points and, if applicable, where you recommend new areas for future research. For most college-level research papers, one or two well-developed paragraphs is sufficient for a conclusion, although in some cases, more paragraphs may be required in summarizing key findings and their significance.

Conclusions. The Writing Center. University of North Carolina; Conclusions. The Writing Lab and The OWL. Purdue University.

Importance of a Good Conclusion

A well-written conclusion provides you with important opportunities to demonstrate to the reader your understanding of the research problem. These include:

• Presenting the last word on the issues you raised in your paper . Just as the introduction gives a first impression to your reader, the conclusion offers a chance to leave a lasting impression. Do this, for example, by highlighting key findings in your analysis that advance new understanding about the research problem, that are unusual or unexpected, or that have important implications applied to practice.
• Summarizing your thoughts and conveying the larger significance of your study . The conclusion is an opportunity to succinctly re-emphasize  the "So What?" question by placing the study within the context of how your research advances past research about the topic.
• Identifying how a gap in the literature has been addressed . The conclusion can be where you describe how a previously identified gap in the literature [described in your literature review section] has been filled by your research.
• Demonstrating the importance of your ideas . Don't be shy. The conclusion offers you the opportunity to elaborate on the impact and significance of your findings. This is particularly important if your study approached examining the research problem from an unusual or innovative perspective.
• Introducing possible new or expanded ways of thinking about the research problem . This does not refer to introducing new information [which should be avoided], but to offer new insight and creative approaches for framing or contextualizing the research problem based on the results of your study.

Bunton, David. “The Structure of PhD Conclusion Chapters.” Journal of English for Academic Purposes 4 (July 2005): 207–224; Conclusions. The Writing Center. University of North Carolina; Kretchmer, Paul. Twelve Steps to Writing an Effective Conclusion. San Francisco Edit, 2003-2008; Conclusions. The Writing Lab and The OWL. Purdue University; Assan, Joseph. "Writing the Conclusion Chapter: The Good, the Bad and the Missing." Liverpool: Development Studies Association (2009): 1-8.

Structure and Writing Style

I.  General Rules

The function of your paper's conclusion is to restate the main argument . It reminds the reader of the strengths of your main argument(s) and reiterates the most important evidence supporting those argument(s). Do this by stating clearly the context, background, and necessity of pursuing the research problem you investigated in relation to an issue, controversy, or a gap found in the literature. Make sure, however, that your conclusion is not simply a repetitive summary of the findings. This reduces the impact of the argument(s) you have developed in your essay.

When writing the conclusion to your paper, follow these general rules:

• Present your conclusions in clear, simple language. Re-state the purpose of your study, then describe how your findings differ or support those of other studies and why [i.e., what were the unique or new contributions your study made to the overall research about your topic?].
• Do not simply reiterate your findings or the discussion of your results. Provide a synthesis of arguments presented in the paper to show how these converge to address the research problem and the overall objectives of your study.
• Indicate opportunities for future research if you haven't already done so in the discussion section of your paper. Highlighting the need for further research provides the reader with evidence that you have an in-depth awareness of the research problem and that further investigations should take place.

Consider the following points to help ensure your conclusion is presented well:

• If the argument or purpose of your paper is complex, you may need to summarize the argument for your reader.
• If, prior to your conclusion, you have not yet explained the significance of your findings or if you are proceeding inductively, use the end of your paper to describe your main points and explain their significance.
• Move from a detailed to a general level of consideration that returns the topic to the context provided by the introduction or within a new context that emerges from the data. 

The conclusion also provides a place for you to persuasively and succinctly restate the research problem, given that the reader has now been presented with all the information about the topic . Depending on the discipline you are writing in, the concluding paragraph may contain your reflections on the evidence presented. However, the nature of being introspective about the research you have conducted will depend on the topic and whether your professor wants you to express your observations in this way.

NOTE : If asked to think introspectively about the topics, do not delve into idle speculation. Being introspective means looking within yourself as an author to try and understand an issue more deeply, not to guess at possible outcomes or make up scenarios not supported by the evidence.

II.  Developing a Compelling Conclusion

Although an effective conclusion needs to be clear and succinct, it does not need to be written passively or lack a compelling narrative. Strategies to help you move beyond merely summarizing the key points of your research paper may include any of the following strategies:

• If your essay deals with a critical, contemporary problem, warn readers of the possible consequences of not attending to the problem proactively.
• Recommend a specific course or courses of action that, if adopted, could address a specific problem in practice or in the development of new knowledge.
• Cite a relevant quotation or expert opinion already noted in your paper in order to lend authority and support to the conclusion(s) you have reached [a good place to look is research from your literature review].
• Explain the consequences of your research in a way that elicits action or demonstrates urgency in seeking change.
• Restate a key statistic, fact, or visual image to emphasize the most important finding of your paper.
• If your discipline encourages personal reflection, illustrate your concluding point by drawing from your own life experiences.
• Return to an anecdote, an example, or a quotation that you presented in your introduction, but add further insight derived from the findings of your study; use your interpretation of results to recast it in new or important ways.
• Provide a "take-home" message in the form of a succinct, declarative statement that you want the reader to remember about your study.

III. Problems to Avoid

Failure to be concise Your conclusion section should be concise and to the point. Conclusions that are too lengthy often have unnecessary information in them. The conclusion is not the place for details about your methodology or results. Although you should give a summary of what was learned from your research, this summary should be relatively brief, since the emphasis in the conclusion is on the implications, evaluations, insights, and other forms of analysis that you make. Strategies for writing concisely can be found here .

Failure to comment on larger, more significant issues In the introduction, your task was to move from the general [the field of study] to the specific [the research problem]. However, in the conclusion, your task is to move from a specific discussion [your research problem] back to a general discussion [i.e., how your research contributes new understanding or fills an important gap in the literature]. In short, the conclusion is where you should place your research within a larger context [visualize your paper as an hourglass--start with a broad introduction and review of the literature, move to the specific analysis and discussion, conclude with a broad summary of the study's implications and significance].

Failure to reveal problems and negative results Negative aspects of the research process should never be ignored. These are problems, deficiencies, or challenges encountered during your study should be summarized as a way of qualifying your overall conclusions. If you encountered negative or unintended results [i.e., findings that are validated outside the research context in which they were generated], you must report them in the results section and discuss their implications in the discussion section of your paper. In the conclusion, use your summary of the negative results as an opportunity to explain their possible significance and/or how they may form the basis for future research.

Failure to provide a clear summary of what was learned In order to be able to discuss how your research fits within your field of study [and possibly the world at large], you need to summarize briefly and succinctly how it contributes to new knowledge or a new understanding about the research problem. This element of your conclusion may be only a few sentences long.

Failure to match the objectives of your research Often research objectives in the social sciences change while the research is being carried out. This is not a problem unless you forget to go back and refine the original objectives in your introduction. As these changes emerge they must be documented so that they accurately reflect what you were trying to accomplish in your research [not what you thought you might accomplish when you began].

Resist the urge to apologize If you've immersed yourself in studying the research problem, you presumably should know a good deal about it [perhaps even more than your professor!]. Nevertheless, by the time you have finished writing, you may be having some doubts about what you have produced. Repress those doubts! Don't undermine your authority by saying something like, "This is just one approach to examining this problem; there may be other, much better approaches that...." The overall tone of your conclusion should convey confidence to the reader.

Assan, Joseph. "Writing the Conclusion Chapter: The Good, the Bad and the Missing." Liverpool: Development Studies Association (2009): 1-8; Concluding Paragraphs. College Writing Center at Meramec. St. Louis Community College; Conclusions. The Writing Center. University of North Carolina; Conclusions. The Writing Lab and The OWL. Purdue University; Freedman, Leora  and Jerry Plotnick. Introductions and Conclusions. The Lab Report. University College Writing Centre. University of Toronto; Leibensperger, Summer. Draft Your Conclusion. Academic Center, the University of Houston-Victoria, 2003; Make Your Last Words Count. The Writer’s Handbook. Writing Center. University of Wisconsin Madison; Miquel, Fuster-Marquez and Carmen Gregori-Signes. “Chapter Six: ‘Last but Not Least:’ Writing the Conclusion of Your Paper.” In Writing an Applied Linguistics Thesis or Dissertation: A Guide to Presenting Empirical Research . John Bitchener, editor. (Basingstoke,UK: Palgrave Macmillan, 2010), pp. 93-105; Tips for Writing a Good Conclusion. Writing@CSU. Colorado State University; Kretchmer, Paul. Twelve Steps to Writing an Effective Conclusion. San Francisco Edit, 2003-2008; Writing Conclusions. Writing Tutorial Services, Center for Innovative Teaching and Learning. Indiana University; Writing: Considering Structure and Organization. Institute for Writing Rhetoric. Dartmouth College.

Writing Tip

Don't Belabor the Obvious!

Avoid phrases like "in conclusion...," "in summary...," or "in closing...." These phrases can be useful, even welcome, in oral presentations. But readers can see by the tell-tale section heading and number of pages remaining to read, when an essay is about to end. You'll irritate your readers if you belabor the obvious.

Assan, Joseph. "Writing the Conclusion Chapter: The Good, the Bad and the Missing." Liverpool: Development Studies Association (2009): 1-8.

Another Writing Tip

New Insight, Not New Information!

Don't surprise the reader with new information in your conclusion that was never referenced anywhere else in the paper and, as such, the conclusion rarely has citations to sources. If you have new information to present, add it to the discussion or other appropriate section of the paper. Note that, although no actual new information is introduced, the conclusion, along with the discussion section, is where you offer your most "original" contributions in the paper; the conclusion is where you describe the value of your research, demonstrate that you understand the material that you’ve presented, and locate your findings within the larger context of scholarship on the topic, including describing how your research contributes new insights or valuable insight to that scholarship.

Assan, Joseph. "Writing the Conclusion Chapter: The Good, the Bad and the Missing." Liverpool: Development Studies Association (2009): 1-8; Conclusions. The Writing Center. University of North Carolina.

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How to Write a Conclusion for a Research Paper

Last Updated: June 29, 2023 Approved

This article was co-authored by Christopher Taylor, PhD . Christopher Taylor is an Adjunct Assistant Professor of English at Austin Community College in Texas. He received his PhD in English Literature and Medieval Studies from the University of Texas at Austin in 2014. wikiHow marks an article as reader-approved once it receives enough positive feedback. This article received 42 testimonials and 82% of readers who voted found it helpful, earning it our reader-approved status. This article has been viewed 2,256,049 times.

The conclusion of a research paper needs to summarize the content and purpose of the paper without seeming too wooden or dry. Every basic conclusion must share several key elements, but there are also several tactics you can play around with to craft a more effective conclusion and several you should avoid to prevent yourself from weakening your paper's conclusion. Here are some writing tips to keep in mind when creating a conclusion for your next research paper.

Sample Conclusions

Writing a basic conclusion.

• Do not spend a great amount of time or space restating your topic.
• A good research paper will make the importance of your topic apparent, so you do not need to write an elaborate defense of your topic in the conclusion.
• Usually a single sentence is all you need to restate your topic.
• An example would be if you were writing a paper on the epidemiology of infectious disease, you might say something like "Tuberculosis is a widespread infectious disease that affects millions of people worldwide every year."
• Yet another example from the humanities would be a paper about the Italian Renaissance: "The Italian Renaissance was an explosion of art and ideas centered around artists, writers, and thinkers in Florence."

• A thesis is a narrowed, focused view on the topic at hand.
• This statement should be rephrased from the thesis you included in your introduction. It should not be identical or too similar to the sentence you originally used.
• Try re-wording your thesis statement in a way that complements your summary of the topic of your paper in your first sentence of your conclusion.
• An example of a good thesis statement, going back to the paper on tuberculosis, would be "Tuberculosis is a widespread disease that affects millions of people worldwide every year. Due to the alarming rate of the spread of tuberculosis, particularly in poor countries, medical professionals are implementing new strategies for the diagnosis, treatment, and containment of this disease ."

• A good way to go about this is to re-read the topic sentence of each major paragraph or section in the body of your paper.
• Find a way to briefly restate each point mentioned in each topic sentence in your conclusion. Do not repeat any of the supporting details used within your body paragraphs.
• Under most circumstances, you should avoid writing new information in your conclusion. This is especially true if the information is vital to the argument or research presented in your paper.
• For example, in the TB paper you could summarize the information. "Tuberculosis is a widespread disease that affects millions of people worldwide. Due to the alarming rate of the spread of tuberculosis, particularly in poor countries, medical professionals are implementing new strategies for the diagnosis, treatment, and containment of this disease. In developing countries, such as those in Africa and Southeast Asia, the rate of TB infections is soaring. Crowded conditions, poor sanitation, and lack of access to medical care are all compounding factors in the spread of the disease. Medical experts, such as those from the World Health Organization are now starting campaigns to go into communities in developing countries and provide diagnostic testing and treatments. However, the treatments for TB are very harsh and have many side effects. This leads to patient non-compliance and spread of multi-drug resistant strains of the disease."

• Note that this is not needed for all research papers.
• If you already fully explained what the points in your paper mean or why they are significant, you do not need to go into them in much detail in your conclusion. Simply restating your thesis or the significance of your topic should suffice.
• It is always best practice to address important issues and fully explain your points in the body of your paper. The point of a conclusion to a research paper is to summarize your argument for the reader and, perhaps, to call the reader to action if needed.

• Note that a call for action is not essential to all conclusions. A research paper on literary criticism, for instance, is less likely to need a call for action than a paper on the effect that television has on toddlers and young children.
• A paper that is more likely to call readers to action is one that addresses a public or scientific need. Let's go back to our example of tuberculosis. This is a very serious disease that is spreading quickly and with antibiotic-resistant forms.
• A call to action in this research paper would be a follow-up statement that might be along the lines of "Despite new efforts to diagnose and contain the disease, more research is needed to develop new antibiotics that will treat the most resistant strains of tuberculosis and ease the side effects of current treatments."

• For example, if you are writing a history paper, then you might discuss how the historical topic you discussed matters today. If you are writing about a foreign country, then you might use the conclusion to discuss how the information you shared may help readers understand their own country.

Making Your Conclusion as Effective as Possible

• Since this sort of conclusion is so basic, you must aim to synthesize the information rather than merely summarizing it.
• Instead of merely repeating things you already said, rephrase your thesis and supporting points in a way that ties them all together.
• By doing so, you make your research paper seem like a "complete thought" rather than a collection of random and vaguely related ideas.

• Ask a question in your introduction. In your conclusion, restate the question and provide a direct answer.
• Write an anecdote or story in your introduction but do not share the ending. Instead, write the conclusion to the anecdote in the conclusion of your paper.
• For example, if you wanted to get more creative and put a more humanistic spin on a paper on tuberculosis, you might start your introduction with a story about a person with the disease, and refer to that story in your conclusion. For example, you could say something like this before you re-state your thesis in your conclusion: "Patient X was unable to complete the treatment for tuberculosis due to severe side effects and unfortunately succumbed to the disease."
• Use the same concepts and images introduced in your introduction in your conclusion. The images may or may not appear at other points throughout the research paper.

• Include enough information about your topic to back the statement up but do not get too carried away with excess detail.
• If your research did not provide you with a clear-cut answer to a question posed in your thesis, do not be afraid to indicate as much.
• Restate your initial hypothesis and indicate whether you still believe it or if the research you performed has begun swaying your opinion.
• Indicate that an answer may still exist and that further research could shed more light on the topic at hand.

• This may not be appropriate for all types of research papers. Most research papers, such as one on effective treatment for diseases, will have the information to make the case for a particular argument already in the paper.
• A good example of a paper that might ask a question of the reader in the ending is one about a social issue, such as poverty or government policy.
• Ask a question that will directly get at the heart or purpose of the paper. This question is often the same question, or some version of it, that you may have started with when you began your research.
• Make sure that the question can be answered by the evidence presented in your paper.
• If desired you can briefly summarize the answer after stating the question. You could also leave the question hanging for the reader to answer, though.

• Even without a call to action, you can still make a recommendation to your reader.
• For instance, if you are writing about a topic like third-world poverty, you can various ways for the reader to assist in the problem without necessarily calling for more research.
• Another example would be, in a paper about treatment for drug-resistant tuberculosis, you could suggest donating to the World Health Organization or research foundations that are developing new treatments for the disease.

Avoiding Common Pitfalls

• These sayings usually sound stiff, unnatural, or trite when used in writing.
• Moreover, using a phrase like "in conclusion" to begin your conclusion is a little too straightforward and tends to lead to a weak conclusion. A strong conclusion can stand on its own without being labeled as such.

• Always state the main argument or thesis in the introduction. A research paper is an analytical discussion of an academic topic, not a mystery novel.
• A good, effective research paper will allow your reader to follow your main argument from start to finish.
• This is why it is best practice to start your paper with an introduction that states your main argument and to end the paper with a conclusion that re-states your thesis for re-iteration.

• All significant information should be introduced in the body of the paper.
• Supporting evidence expands the topic of your paper by making it appear more detailed. A conclusion should narrow the topic to a more general point.
• A conclusion should only summarize what you have already stated in the body of your paper.
• You may suggest further research or a call to action, but you should not bring in any new evidence or facts in the conclusion.

• Most often, a shift in tone occurs when a research paper with an academic tone gives an emotional or sentimental conclusion.
• Even if the topic of the paper is of personal significance for you, you should not indicate as much in your paper.
• If you want to give your paper a more humanistic slant, you could start and end your paper with a story or anecdote that would give your topic more personal meaning to the reader.
• This tone should be consistent throughout the paper, however.

• Apologetic statements include phrases like "I may not be an expert" or "This is only my opinion."
• Statements like this can usually be avoided by refraining from writing in the first-person.
• Avoid any statements in the first-person. First-person is generally considered to be informal and does not fit with the formal tone of a research paper.

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• ↑ http://owl.english.purdue.edu/owl/resource/724/04/
• ↑ http://www.crlsresearchguide.org/18_Writing_Conclusion.asp
• ↑ http://writing.wisc.edu/Handbook/PlanResearchPaper.html#conclusion
• ↑ http://writingcenter.unc.edu/handouts/conclusions/
• ↑ http://writing2.richmond.edu/writing/wweb/conclude.html

About This Article

To write a conclusion for a research paper, start by restating your thesis statement to remind your readers what your main topic is and bring everything full circle. Then, briefly summarize all of the main points you made throughout your paper, which will help remind your readers of everything they learned. You might also want to include a call to action if you think more research or work needs to be done on your topic by writing something like, "Despite efforts to contain the disease, more research is needed to develop antibiotics." Finally, end your conclusion by explaining the broader context of your topic and why your readers should care about it, which will help them understand why your topic is relevant and important. For tips from our Academic co-author, like how to avoid common pitfalls when writing your conclusion, scroll down! Did this summary help you? Yes No

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How to Write a Conclusion for a Research Paper

When you're wrapping up a research paper, the conclusion is like the grand finale of a fireworks show – it's your chance to leave a lasting impression. In this article, we'll break down the steps to help you write a winning research paper conclusion that not only recaps your main points but also ties everything together. Consider it the "So what?" moment – why should people care about your research? Our professional essay writers will guide you through making your conclusion strong, clear, and something that sticks with your readers long after they've put down your paper. So, let's dive in and ensure your research ends on a high note!

What Is a Conclusion in a Research Paper

In a research paper, the conclusion serves as the final segment, where you summarize the main points and findings of your study. It's not just a repetition of what you've already said but rather a chance to tie everything together and highlight the significance of your research. As you learn how to start a research paper , a good conclusion also often discusses the implications of your findings, suggests potential areas for further research, and leaves the reader with a lasting impression of the importance and relevance of your work in the broader context of the field. Essentially, it's your last opportunity to make a strong impact and leave your readers with a clear understanding of the significance of your research. Here’s a research paper conclusion example:

In conclusion, this research paper has navigated the intricacies of sustainable urban development, shedding light on the pivotal role of community engagement and innovative planning strategies. Through applying qualitative and quantitative research methods, we've uncovered valuable insights into the challenges and opportunities inherent in fostering environmentally friendly urban spaces. The implications of these findings extend beyond the confines of this study, emphasizing the imperative for continued exploration in the realms of urban planning and environmental sustainability. By emphasizing both the practical applications and theoretical contributions, this research underscores the significance of community involvement and forward-thinking strategies in shaping the future of urban landscapes. As cities evolve, incorporating these insights into planning and development practices will create resilient and harmonious urban environments.

Conclusion Outline for Research Paper

This outline for a research paper conclusion provides a structured framework to ensure that your ending effectively summarizes the key elements of your research paper and leaves a lasting impression on your readers. Adjust the content based on the specific requirements and focus of your research.

Restate the Thesis Statement

• Briefly restate the main thesis or research question.
• Emphasize the core objective or purpose of the study.

Summarize Key Findings

• Recap the main points and key findings from each section of the paper.
• Provide a concise overview of the research journey.

Discuss Implications

• Explore the broader implications of the research findings.
• Discuss how the results contribute to the existing body of knowledge in the field.

Address Limitations

• Acknowledge any limitations or constraints encountered during the research process.
• Explain how these limitations may impact the interpretation of the findings.

Suggest Areas for Future Research

• Propose potential directions for future studies related to the topic.
• Identify gaps in the current research that warrant further exploration.

Reaffirm Significance

• Reaffirm the importance and relevance of the research in the broader context.
• Highlight the practical applications or real-world implications of the study.

Concluding Statement

• Craft a strong, memorable closing statement that leaves a lasting impression.
• Sum up the overall impact of the research and its potential contribution to the field.

Study the full guide on how to make a research paper outline here, which will also specify the conclusion writing specifics to improve your general prowess.

Tips on How to Make a Conclusion in Research

Here are key considerations regarding a conclusion for research paper to not only recap the primary ideas in your work but also delve deeper to earn a higher grade:

• Provide a concise recap of your main research outcomes.
• Remind readers of your research goals and their accomplishments.
• Stick to summarizing existing content; refrain from adding new details.
• Emphasize why your research matters and its broader implications.
• Clearly explain the practical or theoretical impact of your findings.
• Prompt readers to reflect on how your research influences their perspective.
• Briefly discuss the robustness of your research methods.
• End with a suggestion for future research or a practical application.
• Transparently address any constraints or biases in your study.
• End on a powerful note, leaving a memorable impression on your readers.

For your inspiration, we’ve also prepared this research proposal example APA , which dwells on another important aspect of research writing.

How to Write a Research Paper Conclusion

As you finish your research paper, the conclusion takes center stage. In this section, we've got five practical tips for writing a conclusion for a research paper. We'll guide you through summarizing your key findings, revisiting your research goals, discussing the bigger picture, addressing any limitations, and ending on a powerful note. Think of it as your roadmap to creating a conclusion that not only wraps up your research but also leaves a lasting impact on your readers. Let's dive in and make sure your conclusion stands out for all the right reasons!

Synthesize Core Discoveries. Initiate your conclusion by synthesizing the essential discoveries of your research. Offer a succinct recapitulation of the primary points and outcomes you have elucidated in your paper. This aids in reinforcing the gravity of your work and reiterates the pivotal information you have presented.

Revisit Research Objectives. Revisit the research objectives or questions you outlined at the beginning of your paper. Assess whether you have successfully addressed these objectives and if your findings align with the initial goals of your research. This reflection helps tie your conclusion back to the purpose of your study.

Discuss Implications and Contributions. Discuss the broader implications of your research and its potential contributions to the field. Consider how your findings might impact future research, applications, or understanding of the subject matter. This demonstrates the significance of your work and places it within a larger context.

Address Limitations and Future Research. Acknowledge any limitations in your study, such as constraints in data collection or potential biases. Briefly discuss how these limitations might have affected your results. Additionally, suggest areas for future research that could build upon your work, addressing any unanswered questions or unexplored aspects. This demonstrates a thoughtful approach to your research.

End with a Strong Conclusion Statement. Conclude your research paper with a strong and memorable statement that reinforces the key message you want readers to take away. This could be a call to action, a proposal for further investigation, or a reflection on the broader significance of your findings. Leave your readers with a lasting impression that emphasizes the importance of your research. Remember that you can buy a research paper anytime if you lack time or get stuck in writer’s block.

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Stylistic Devices to Use in a Conclusion

Discover distinctive stylistic insights that you can apply when writing a conclusion for a research paper:

• Rhetorical Questions. When using rhetorical questions, strategically place them to engage readers' minds. For instance, you might pose a question that prompts reflection on the broader implications of your findings, leaving your audience with something to ponder.
• Powerful Language. Incorporate strong language to convey a sense of conviction and importance. Choose words that resonate with the overall tone of your research and amplify the significance of your conclusions. This adds weight to your key messages.
• Repetitions. Repetitions can be employed to reinforce essential ideas. Reiterate key phrases or concepts in a way that emphasizes their importance without sounding redundant. This technique serves to drive home your main points.
• Anecdotes. Integrating anecdotes into your conclusion can provide a human touch. Share a brief and relevant story that connects with your research, making the information more relatable and memorable for your audience.
• Vivid Imagery. Lastly, use vivid imagery to paint a picture in the minds of your readers. Appeal to their senses by describing scenarios or outcomes related to your research. This creates a more immersive and lasting impression.

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How to Make a Conclusion Logically Appealing

Knowing how to write a conclusion for a research paper that is logically appealing is important for leaving a lasting impression on your readers. Here are some tips to achieve this:

Logical Sequencing

• Present your conclusion in a structured manner, following the natural flow of your paper. Readers should effortlessly follow your thought process, making your conclusion more accessible and persuasive.

Reinforce Main Arguments

• Emphasize the core arguments and findings from your research. By reinforcing key points, you solidify your stance and provide a logical culmination to your paper.

Address Counterarguments

• Acknowledge and address potential counterarguments or limitations in your research. Demonstrate intellectual honesty and strengthen your conclusion by preemptively addressing potential doubts.

Connect with Introduction

• Revisit themes or concepts introduced in your introduction to create a cohesive narrative, allowing readers to trace the logical progression of your research from start to finish.

Propose Actionable Insights

• Suggest practical applications or recommendations based on your findings. This will add a forward-looking dimension, making your conclusion more relevant and compelling.

Highlight Significance

• Clearly articulate the broader implications of your research to convey the importance of your work and its potential impact on the field, making your conclusion logically compelling.

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Avoid These Things When Writing a Research Paper Conclusion

As you write your conclusion of research paper, there’s a list of things professional writers don’t recommend doing. Consider these issues carefully:

• Repetition of Exact Phrases
• Repetitively using the same phrases or sentences from the main body. Repetition can make your conclusion seem redundant and less engaging.
• Overly Lengthy Summaries
• Providing excessively detailed summaries of each section of your paper. Readers may lose interest if the conclusion becomes too long and detailed.
• Unclear Connection to the Introduction
• Failing to connect the conclusion back to the introduction. A lack of continuity may make the paper feel disjointed.
• Adding New Arguments or Ideas
• Introducing new arguments or ideas that were not addressed in the body. This can confuse the reader and disrupt the coherence of your paper.
• Overuse of Complex Jargon
• Using excessively complex or technical language without clarification. Clear communication is essential in the conclusion, ensuring broad understanding.
• Apologizing or Undermining Confidence
• Apologizing for limitations or expressing doubt about your work. Maintain a confident tone; if limitations exist, present them objectively without undermining your research.
• Sweeping Generalizations
• Making overly broad or unsupported generalizations. Such statements can weaken the credibility of your conclusion.
• Neglecting the Significance
• Failing to emphasize the broader significance of your research. Readers need to understand why your findings matter in a larger context.
• Abrupt Endings
• Concluding abruptly without a strong closing statement. A powerful ending leaves a lasting impression; avoid a sudden or weak conclusion.

Research Paper Conclusion Example

That covers the essential aspects of summarizing a research paper. The only remaining step is to review the conclusion examples for research paper provided by our team.

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Final Thoughts

In conclusion, the knowledge of how to write the conclusion of a research paper is pivotal for presenting your findings and leaving a lasting impression on your readers. By summarizing the key points, reiterating the significance of your research, and offering avenues for future exploration, you can create a conclusion that not only reinforces the value of your study but also encourages further academic discourse. Remember to balance brevity and completeness, ensuring your conclusion is concise yet comprehensive. Emphasizing the practical implications of your research and connecting it to the broader academic landscape will help solidify the impact of your work. Pay someone to write a research paper if you are having a hard time finishing your coursework on time.

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OASIS: Writing Center

Writing a paper: conclusions, writing a conclusion.

A conclusion is an important part of the paper; it provides closure for the reader while reminding the reader of the contents and importance of the paper. It accomplishes this by stepping back from the specifics in order to view the bigger picture of the document. In other words, it is reminding the reader of the main argument. For most course papers, it is usually one paragraph that simply and succinctly restates the main ideas and arguments, pulling everything together to help clarify the thesis of the paper. A conclusion does not introduce new ideas; instead, it should clarify the intent and importance of the paper. It can also suggest possible future research on the topic.

An Easy Checklist for Writing a Conclusion

It is important to remind the reader of the thesis of the paper so he is reminded of the argument and solutions you proposed.

Think of the main points as puzzle pieces, and the conclusion is where they all fit together to create a bigger picture. The reader should walk away with the bigger picture in mind.

Make sure that the paper places its findings in the context of real social change.

Make sure the reader has a distinct sense that the paper has come to an end. It is important to not leave the reader hanging. (You don’t want her to have flip-the-page syndrome, where the reader turns the page, expecting the paper to continue. The paper should naturally come to an end.)

No new ideas should be introduced in the conclusion. It is simply a review of the material that is already present in the paper. The only new idea would be the suggesting of a direction for future research.

Conclusion Example

As addressed in my analysis of recent research, the advantages of a later starting time for high school students significantly outweigh the disadvantages. A later starting time would allow teens more time to sleep--something that is important for their physical and mental health--and ultimately improve their academic performance and behavior. The added transportation costs that result from this change can be absorbed through energy savings. The beneficial effects on the students’ academic performance and behavior validate this decision, but its effect on student motivation is still unknown. I would encourage an in-depth look at the reactions of students to such a change. This sort of study would help determine the actual effects of a later start time on the time management and sleep habits of students.

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How to Write a Conclusion for a Research Paper that Resonates

The conclusion of a research paper is a crucial part of the entire document. The final section summarizes the main points, restates the thesis statement, and provides closure to the reader. Writing a strong conclusion for a research paper can be challenging because you must bring together all the ideas you’ve presented concisely and compellingly. Don’t fret, as we’ll let you know how to write a conclusion for a research paper like a professional  paper writing service  provider. So, let’s dive in!

Table of Contents

The Ultimate Guide on How to Write a Conclusion for a Research Paper

A great conclusion makes your paper stand out and leaves a lasting impression on your readers. Let us help you figure out how to write a killer conclusion for your research paper.

Four Important Elements of a Research Paper Conclusion

These are the essential elements you must include in the conclusion of your  research paper writing  for a lasting impression.

Restate the Thesis Statement

It’s really important to remind readers of the main argument in your paper. You should state the  thesis statement  in the intro and then again in the conclusion. But don’t just copy and paste the same words! It’s better to rephrase it in a slightly different way so readers know you understand the topic.

Summarize the Main Points of the Research Paper

It’s important to sum up the paper’s main points to show the reader it’s covered the topic well. Just use the topic sentences from the body paragraphs and make it brief; that should do it.

Discuss the Implications of the Research

It’s important to cover the implications of the research so the reader can understand the bigger picture. This part should emphasize the real-world or theoretical implications of the research and explain why the results are important. These implications can involve multiple topics, such as policy, practices, theories, or further research.

Provide Closure to the Reader

A satisfying research paper conclusion is the key to its success. This last section should link together the main points made throughout the paper and make the reader feel like the paper has come to its natural conclusion. It’s a great idea to finish the conclusion with a thought-provoking statement, an invitation to take action or a question that will leave the reader pondering.

For Example:

Tips for Writing A Strong Conclusion

These are the expert tips to help you write a strong conclusion for your research paper:

Tip 1: Keep it Concise and to The Point

Make sure your conclusion is short and sweet, summing up the main points of your research paper without adding anything new. Don’t use different words or phrases to fill up space – say what needs to be said in a simple, straightforward way.

Tip 2: Use language that is clear and easy to understand

Make sure everyone easily understands your conclusion. Don’t use technical words. Stick to the main points and make sure everyone can follow along.

Tip 3: Avoid Introducing New Information

Your conclusion should wrap up the ideas you’ve presented in your paper, not add anything new. Summarize the main ideas and arguments that you’ve presented and show how they back up your thesis.

Tip 4: Use a Strong Concluding Sentence

Wrapping up your paper with a strong conclusion helps tie everything together and leaves an impact on the reader. Why not finish with a thought-provoking question, a call to action or a powerful statement? It’ll be sure to stick with them.

Common Mistakes to Avoid

Here are some common mistakes you should avoid when writing a conclusion for your research paper:

Don’t Repeat the Information

In your research paper conclusion, try not to copy what’s already been said in the body of the paper. Sum up the main points, but don’t just repeat them word for word. Show how the evidence and ideas in the paper back up the thesis.

Avoid Including Personal Opinions and or Biases

Be careful not to let your feelings sneak into the conclusion. Stick to the facts and sum up the main points of your paper instead of giving your own opinion. Keep it objective!

Don’t Use Weak Language or Cliches:

Don’t use weak language or cliches like “in conclusion” or “it can be said that.” Also, don’t say “more research is needed” since it makes your conclusion seem unfulfilled. Instead, be clear about when and where you’re talking about and emphasize the importance of your research.

Example of Good Research Paper Conclusions

It’s important to make a lasting impression on your reader, so having a good conclusion to your research paper is key. Here are some examples of what makes a strong conclusion and the elements that make it effective:

Example 1 – A Research Paper on The Effects of Social Media on Mental Health:

Through the research analysis, it is clear that social media use can significantly negatively affect mental health. To address this issue, individuals and society need to recognize social media’s impact and take steps to mitigate its negative effects. This research highlights the need for further investigation into the relationship between social media and mental health, as well as the development of strategies to promote healthy social media use.

Example 2 – A Research Paper on The Benefits of Exercise:

The findings of this study demonstrate the numerous benefits of regular exercise, including improved cardiovascular health, increased strength, and reduced stress levels. These benefits highlight the importance of physical activity for individuals of all ages and abilities. Individuals and society need to prioritize exercise and promote physical activity to improve overall health and well-being.

Finishing your research paper with a strong conclusion is key to leaving a lasting impact on your reader. We are summarizing the conclusion for a research paper in brief points.

•  Sum up the main points of your paper and restate your thesis statement.
• Think about the implications of your research and provide closure for your reader.
• Keep your language clear and avoid introducing new info.
• Use a strong conclusion sentence, and don’t make mistakes like repeating yourself or adding personal opinions or bias.

Hopefully you won’t need to search how to write conclusion in research again. Still, if you need help with a conclusion in research paper, you can order today so  our writers  can assist you immediately.

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How to Write a Conclusion for a Research Paper: Examples & Tips

You might be wondering about how to write a conclusion paragraph for a research paper. It may seem like your readers should understand your main arguments by the end, so there is no need for it. However, there are several aspects that prove the importance of a conclusion section in research.

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Its first and primary function is, of course, a summary of all the main ideas and evidence in the paper. Sometimes research can be quite lengthy so putting all the thoughts you want to share in one place is very handy. Moreover, the conclusion shows how important your work is and suggests new ways of looking at the problem.

Our guide and research paper conclusion example are here to help you with your assignment!

• ❗ Importance of a Conclusion
• 👣 Writing Steps
• 📑 Conclusion Types & Examples
• ❌ Common Mistakes

🔗 References

❗ importance of a conclusion in a research paper.

A conclusion intends to remind the readers about the main arguments and findings of the whole paper. However, it also highlights the significance of the work. Both these functions help create a long-lasting, memorable impression from your research paper , so always include this part and try to think of the ways to make it even more effective.

Since having a strong concluding paragraph is so crucial for the overall success, you might want to check out a step-by-step guide on writing it. It can assure you don’t miss any vital moments. Moreover, you need to find out what conclusion type would be the best!

👣 How to Write a Conclusion for a Research Paper Step by Step

Below are only a few simple steps that can allow you to write the most persuasive research paper.

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📑 Types & Examples of Research Paper Conclusions

You may be assigned to write a persuasive or argumentative paper. Or your professor might ask you to develop an analytical or comparative research paper.

Should you write their conclusions in the same way? The answer is “No”. When you write different types of assignments, you need different conclusions.

Argumentative Research Paper Conclusion

To write an excellent argumentative paper conclusion, you need to highlight the most persuasive and strong arguments you have — no need to add many details. In addition, don’t forget you should include the essential components of the conclusion, such as paraphrasing your thesis statement, which points out your opinion on the chosen topic. If you used a strong thesis statement generator , it won’t be hard to do.

Argumentative Research Paper Conclusion Example

Right now, Earth is facing the issue of the sixth extinction, which causes numerous species to fade every day. There are at least three ideas people might use to prevent their total extinction in the next fifty years. More ways of recycling, new approaches to plastic production, and conservation of species could be life-saving.

Analytical Research Paper Conclusion

First, you should restate your thesis statement and summarize the critical points of your arguments. The main difference between the analytical research paper conclusion and other types is that there should definitely be a highlight of a broader context. It means you can add some meaning to the findings.

Analytical Research Paper Conclusion Example

Elon Musk has made a revolution in the way we pay, drive, and even fly. His ideas come only from the desire to make things easier, but eventually, they change the world. Musk first thought about PayPal when he was a student, and now it’s one of the most popular online payment systems. The same with Tesla cars.

Comparative Research Paper Conclusion

An effective comparative paper conclusion requires some analytical skills. You need to be very careful in looking through facts to clearly formulate your findings. Moreover, the sources need to be trustworthy. And, as usual, you need to add a paraphrased thesis statement and a few words about the importance of your study research.

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Comparative Research Paper Conclusion Example

Electric cars are proven to be more efficient and effective than gas cars. Not only do they produce fewer emissions, but the drivers reach their destination point faster. Moreover, gas cars are more expensive to maintain. It all derives from the specifics of the electric cars’ engines, which are much simpler.

❌ Common Mistakes You Should Avoid

Are you ready to pass your writing? Wait! Have you checked it for the most common mistakes? If no, below are several general errors you should avoid.

• The Conclusion – Organizing Academic Research Papers
• Conclusions – UNC Writing Center
• Conclusions // Purdue Writing Lab
• Writing the conclusion – Research & Learning Online
• Writing a Research Paper – The Writing Center – UW–Madison
• How to Structure & Organize Your Paper
• Writing Conclusions: Writing Guides
• Ending the Essay: Conclusions
• Tips for Writing Policy Papers – Stanford Law School
• A Process Approach to Writing Research Papers
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Very, very useful website for students. I appreciate people who kindly share brilliant writing tips with others! Thanks a lot!

Great article! It helped me to complete my research papers conclusion that was a real nightmare for me! Thank you so much for it!

I was on my way to completing my research paper and going to finish the conclusion by copy-pasting the introduction. Thank God, I wanted to read some articles on conclusion writing. After reading your post on this question, I completed my conclusion following your instructions. Believe my research paper is worth an excellent mark!

In response to a comment from Lynn: Thank you for noting this unfortunate mistake in the text. Obviously, we spend a lot of time compiling, writing, and editing materials, but there’s always room for a simple human error! Thanks again, and have a great day! 🙂

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• Course Description
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Theme by Anders Norén

Project: Final Report

Project report.

Due: Wednesday, 4/24

Example report in box folder, linked here

General Directions

The final report is intended to provide a comprehensive account of your collaborative course project in data science. The report should demonstrate your ability to apply the data science skills you have learned to a real-world project holistically, from posing research questions and gathering data to analysis, visualization, interpretation, and communication. The report should stand on its own so that it makes sense to someone who has not read your proposal or prototype.

The report should contain at least the parts defined below. In terms of length, it should be 5-7 pages using standard margins (1 in.), font (11-12 pt), and line spacing (1-1.5). A typical submission is around 3-4 pages of text and 5-7 pages overall with tables and figures. It is important to stay within the page limit, as practicing being succinct is an important skill. Your final report should also have a descriptive title, not “CS216 Project Report”. You should convert your written report to a pdf and upload it to Gradescope under the assignment “Project Final Report” by the due date, and assign the appropriate pages to questions in the grading rubric. Be sure to include your names and NetIDs in your final document and use the group submission feature on Gradescope. You do not need to upload your accompanying data, code, or other supplemental resources demonstrating your work to Gradescope; instead, your report should contain instructions on how to access these resources (see the Results and Methods section below for more details).

In general, your approach to this report should be to write as if you had “planned this as your project all along.” A report is not a chronological story of your project, it is a summary of what you did where the “story” serves the reader’s comprehension.

• E (Exemplary, 20pts) – Work that meets all requirements in terms of formatting and sections.
• S (Satisfactory, 19 pts) – Work that meets all requirements but is over 7 pages.
• N (Not yet, 12pts) – Does not meet all requirements.
• U (Unassessable, 4pts) –  Missing at least one section.

Part 1: Introduction and Research Questions (15 points)

Your final report should begin by introducing your topic and restating your research question(s) as in your proposal. As before, your research question(s) should be (1) substantial, (2) feasible, and (3) relevant. In contrast to the prior reports, the final report does not need to explicitly justify that the research questions are substantial and feasible in the text ; your results should demonstrate both of these points. Therefore, you should remove that text to save space.

You should still explicitly justify how your research questions are relevant. In other words, be sure to explain the motivation of your research questions. Remember that relevant research questions address a subject of importance and interest within the scientific community or broader society. Additionally, we are looking for why your group believes this research project is worthwhile to your time in this course.

You can start with the text from your prototype, but you should update your introduction and research questions to reflect changes in or refinements of the project vision. You should not state specific updates, rather, write the report as the final product and the prior milestones do not exist. Pretend the readers are unaware of the prior milestones. If you feel like an explanation of changes since the prototype is warranted, place that in the appendix. Your introduction should be sufficient to provide context for the rest of your report.

• E (Exemplary, 15pts) – Comprehensive introduction with clearly labeled, up-to-date research questions and a justification for how the research questions are relevant. Report  introduction can stand alone without references to prior versions of the project; no text for explicit justifications for “substantial” and “feasible” are made for the research question(s).   
• S (Satisfactory, 14pts) – Comprehensive introduction with clearly labeled, updated research questions and a justification for how the research questions are relevant. The introduction and research questions may not have been refined from the prototype (they have still kept reasoning for why their research questions are substantial and feasible).
• N (Not yet, 9pts) – Incomplete introduction where the research questions or justification are missing pieces, but at least some of it is present. Or the justification is clearly not reasonable.
• U (Unassessable, 3pts) – Incomplete introduction where it is entirely missing the research questions or justification or does not demonstrate meaningful effort.

Part 2: Data Sources (15 points)

Discuss the data you have collected and are using to answer your research questions. Be specific: name the datasets you are using, the information they contain, and where they were collected from / how they were prepared. You can begin with the text from your prototype, but be sure to update it to fit the vision for your final project.

• E (Exemplary, 15pts) – Origins of data are properly specified, cited, and relevant to answering the research question(s). If any significant data wrangling, cleaning, or other data preparation was done, these processes are explained.
• S (Satisfactory, 14pts) – Origins of data are properly specified and cited. However, the justification is not clear why the data is relevant to the proposed research question(s). If any significant data wrangling, cleaning, or other data preparation was done, these processes are explained.
• N (Not yet, 9pts) – Poorly specified data sources or the justification for using that data set or the methods to acquire the data is lacking. No discussion of preparing the dataset.
• U (Unassessable, 3pts) – Data sources or methods to acquire data are missing or do not demonstrate meaningful effort.

Part 3: What Modules Are You Using? (15 points)

Your project should utilize concepts from modules we have covered in this course to answer your research question(s). We will assume you will use modules 1 (Python), 2 (Numpy/Pandas), and 5 (Probability).  Your final report should state at least 3 more modules that you have utilized for your project. Each module should have a short description of how you used the knowledge in this module and a justification for that use. In addition, include what specific concepts from the module you used and at what stage of your project you mostly used this module. Potential stages include, but are not limited to: data gathering, data cleaning, data investigation, data analysis, and final report.

• Module 3: Visualization
• Module 4: Data Wrangling
• Module 6: Combining Data
• Module 7: Statistical Inference
• Module 8: Prediction & Supervised Machine Learning
• Module 9: Databases and SQL
• Module 10: Deep Learning

Your overall report should clearly show that you used the modules discussed in this section. You should add any additional modules used and update the existing modules to be more specific to the different tasks and stages of your projects that changed since your prototype.

• E (Exemplary, 15pts) – States at least 3 modules. For each module, they provide an updated (1) short description of how they used the module, (2) justification for using this module, (3) specific concepts they used, (4) what stage they used it, and (5) clearly implemented it in the final report. 
• S (Satisfactory, 14pts) – States at least 3 modules. For each module, they provide an updated (1) short description of how they used the module, (2) justification for using this module, (3) what concepts they used and (4) what stage they used it. Less than 3 modules are clearly implemented in the final report. 
• N (Not yet, 9pts) – States at least 3 modules. For each module, they provide an updated (1) short description of how they used the module, (2) justification for using this module, (3) what concepts they used and (4) what stage they used it. Only one module is clearly implemented in the final report.
• U (Unassessable, 3pts) – Does not meet the Not Yet criteria.

Part 4: Results and Methods (15 points)

This is likely to be the longest section of your paper at multiple pages. The results and methods section of your report should explain your detailed results and the methods used to obtain them. Where possible, results should be summarized using clearly labeled tables or figures and supplemented with written explanations of the significance of the results with respect to the research questions outlined previously. Please note that a screenshot of your dataset does not count as a table or figure and should not be included in your final report.

Your description of your methods should be specific. For example, if you scraped multiple web databases, merged them, and created a visualization, then you should explain how each step was conducted in enough detail that an informed reader could reasonably be expected to reproduce your results with time and effort. Just saying, “we cleaned the data and dealt with missing values” or “we built a predictive model” is insufficient detail.

Your report should also contain instructions on how to access your full implementation (that is, your code, data, and any other supplemental resources like additional charts or tables). The simplest way to do so is to include a link to the box folder, GitLab repo, or whatever other platforms your group is using to house your data and code.

• E (Exemplary, 15pts) – Results are thoroughly discussed using clearly labeled tables or figures followed by written descriptions. Specific explanation of how the results were generated and from what data. Link to code/data to create charts or visualizations is provided. 
• S (Satisfactory, 14pts) – Results are thoroughly discussed using clearly labeled tables or figures followed by written descriptions. Explanation of how the results were generated may lack some specification or it is somewhat unclear as to what data the results are from. Link provided.
• N (Not yet, 9pts) – Results are discussed using tables with missing labels or lacking written descriptions. It is unclear how the results were generated and from what data.
• U (Unassessable, 3pts) – Results are missing or do not demonstrate meaningful effort.

Part 5: Limitations and Future Work (10 points)

In this part, you should discuss any important limitations or caveats to your results with respect to answering your research questions. For example, if you don’t have as much data as you would like or are unable to fairly evaluate the performance of a predictive model, explain and contextualize those limitations. You may want to consider any ethical implications or potential biases of your results as well. 

Finally, provide a brief discussion of future work. This could explain how future research might address the limitations you outline, or it could pose additional follow-up research questions based on your results so far. In short, explain how an informed reader (such as a peer in the class) could improve on and extend your results.

• E (Exemplary, 10pts) – Comprehensive and explicit discussion of important limitations and caveats to results. Brief discussion of future work and how results could be extended and improved upon.
• S (Satisfactory, 9pts) – Discussion of important limitations and caveats to results could be improved or the discussion of future work and how results could be extended and improved upon lacks some specification.
• N (Not yet, 6pts) –  Incomplete discussion of important limitations and caveats to results. Discussion of future work and how results could be extended and improved upon may lack some specification.
• U (Unassessable, 2pts) – Limitations and future work are missing or do not demonstrate meaningful effort.

Part 6: Conclusion (5 points)

Provide a brief (one or two paragraphs) summary of your results. This summary of results should address all of your research questions.

If one of your research questions was “Did COVID-19 result in bankruptcy in North Carolina during 2020?” then a possible (and purely hypothetical) summary of results might be:

We aggregate the public records disclosures of small businesses in North Carolina from January 2019 to December 2020 and find substantial evidence that COVID-19 did result in a moderate increase in bankruptcy during 2020. This increase is not geographically uniform and is concentrated during summer and fall 2020. We also examined the impact of federal stimulus but cannot provide an evaluation of its impact from the available data.

• E (Exemplary, 10pts) – Research questions are clearly and completely addressed through a summary of results. 
• S (Satisfactory, 9pts) – Research questions are clearly addressed through a summary of results. The results may be lacking in completely answering the research questions.
• N (Not yet, 6pts) –  Research questions are somewhat addressed through a summary of results. The results are lacking in completely answering the research questions. Or the results of one of the research questions is missing.
• U (Unassessable, 2pts) – Conclusion is missing or does not demonstrate meaningful effort.

(Optional) Part 7: Appendix of additional figures, tables, and updates summary.

If you are struggling to keep your report within the 5-7 page limit, you may move some (not all) of your figures and tables to an optional appendix that will not count against your page limit. However, your report should stand on its own without the appendix . The appendix is for adding more nuance to your results, not to give you more space to talk about your results. Succinctness is an important skill to practice when doing data science. Your grader is not expected to look at the appendix when grading.

If you strongly feel like a summary of project updates since the proposal is required, you may put them in this appendix as well and mention they are in the appendix in the introduction.

Checklist Before You Submit:

• 5-7 pages in length
• Standard margins (1 in.)
• Font size is 11-12 pt
• Line spacing is 1-1.5
• Final document is a pdf
• Descriptive project title
• Do you feel as if this part meets the requirements of E (Exemplary) or S (Satisfactory) ?

Author Joey Scarpa

Posted March 30, 2024 — 4:30 pm

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• Open access
• Published: 01 April 2024

Cortical alterations associated with lower response to methylphenidate in adults with ADHD

• V. Parlatini   ORCID: orcid.org/0000-0002-4754-2494 1 , 2 , 3 , 4   na1 ,
• D. S. Andrews 1 , 2 , 5   na1 ,
• C. M. Pretzsch   ORCID: orcid.org/0000-0002-2761-6628 1 , 2 , 3 ,
• M. Arenella 1 , 2 , 3 ,
• E. Daly   ORCID: orcid.org/0000-0003-3625-3467 1 , 2 , 3 ,
• C. Ecker 6 &
• D. G. Murphy   ORCID: orcid.org/0000-0002-6664-7451 1 , 2 , 3  

Nature Mental Health ( 2024 ) Cite this article

Metrics details

• Developmental disorders

Neurodevelopmental conditions such as attention deficit hyperactivity disorder (ADHD) vary among individuals. For instance, variation exists in clinical response to methylphenidate (MPH) treatment, especially in adults, but the biological basis of this variability is poorly understood. In this longitudinal structural imaging study, we showed that pre-treatment neuroanatomical measures were associated with response to MPH at two months in 60 adults with ADHD. We compared anatomy with that of 23 controls and examined whether differences were enriched for genes linked to MPH dynamics and brain cells. Individuals with ADHD differed from controls in cortical volume and thickness, predominantly in temporo-parietal regions. Treatment non-responders differed from responders and controls in fronto-temporo-parieto-occipital regions and such differences were associated with reduced improvement on inattentive symptoms. These novel findings suggest that variation in neuroanatomy is associated with varying treatment responses. Group differences in cortical thickness were enriched for biologically plausible genes, including those supporting noradrenaline transport, a target of MPH.

Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental condition characterized by inattentive and/or hyperactive-impulsive symptoms. These typically manifest in childhood but persist in up to 65% of adults 1 . The prevalence of adult ADHD is approximately 2 4%. Stimulants such as methylphenidate (MPH) are the first line of treatment. They modulate dopamine and noradrenaline transmission in striato-cortical regions 3 , 4 , 5 . Specifically, MPH blocks both the dopamine transporter (DAT) and noradrenaline (norepinephrine) transporter (NET) through allosteric binding (that is, at a different site from that of the endogenous neurotransmitter), and thus inhibits both catecholamines reuptake and increases their availability in the synaptic cleft 3 , 6 , 7 . This is turn increases the endogenous stimulation of dopamine and noradrenaline receptors, which optimizes striato-cortical function (for example, top-down regulation of attention, response inhibition and motivation) 8 , 9 , 10 . Methylphenidate is generally effective in improving ADHD symptoms, but randomized controlled trials have reported that more than one-third of adults do not respond 11 . A recent meta-analysis also confirmed lower response rates in adults than in children 12 . This has been associated with an increased risk of negative outcomes, including occupational failure, criminal behavior and substance misuse 13 , 14 . Yet the biological mechanisms underlying variation in adult treatment response are poorly understood.

Different neurobiological characteristics have been suggested to contribute to the varying treatment response in ADHD, including variants of genes encoding DAT ( SLC6A3 ) and NET ( SLC6A2 ) 15 ; DAT epigenetic alterations 16 ; theta oscillations 17 , 18 ; and resting-state fronto-striatal functional connectivity 19 . However, the studies were primarily focused on children 20 and thus the findings may not apply to the adult population 21 . Here we test whether heterogeneity in brain anatomy may contribute to variation in adult treatment response. Most structural magnetic resonance imaging (MRI) studies have so far focused on ADHD versus control comparisons without investigating the treatment response, and mainly included children. For instance, meta-analyses have highlighted lower total and regional grey matter volumes in the basal ganglia and in fronto-parieto-occipital regions in young people with ADHD compared with neurotypical controls 22 , 23 , 24 , 25 , 26 . They also suggested that increasing age is associated with less evident volumetric alterations 24 , 25 . Recent large multicentre studies also confirmed diffuse but subtle morphometric alterations in cortico-subcortical regions in children with ADHD, but could not identify group differences in adults 27 , 28 . The former study focused on the total intracranial volume and subcortical structures, and reported smaller total and subcortical volumes, including in the amygdala, accumbens, putamen, caudate and hippocampus. The latter study reported lower surface area measures in fronto-temporo-cingulate regions, and lower cortical thickness in the temporal pole and fusiform gyrus. Findings were not affected by current stimulant treatment 27 , 28 . These observations are in line with the hypothesis that ADHD symptoms are related to a maturational delay of brain regions involved in cognitive and motor functions 27 , 29 . Nevertheless, ADHD is a highly heterogeneous condition and past studies have suggested that anatomical variation exists (even in adults), and that more pronounced alterations may be associated with co-morbidities or symptom persistence 30 , 31 . In summary, most neuroanatomical investigations have focused on group comparisons with controls, yielding inconsistent or no results, especially in adults. There is therefore an increasing need to parse neuroanatomical heterogeneity, perhaps especially regarding variation in treatment response.

There are limited structural imaging studies on individuals with ADHD that compare treatment responders and non-responders. A small study in children reported that the volume of the caudate and nucleus accumbens were reduced in non-responders compared with responders 32 . Similarly, a more recent retrospective MRI study including both children and adults observed smaller left putamen and larger precuneus volumes in non-responders than responders 33 . These studies represent valuable first steps and suggest that anatomical differences may underpin the variation in treatment response. We hypothesize that this may also apply to adults with ADHD because, although case-control brain anatomical differences decrease with age—perhaps especially in the basal ganglia 24 , 25 —cortical alterations have even been reported in adults. For instance, a meta-analysis of whole brain voxel-based morphometry studies indicated lower volumes of the ventromedial prefrontal cortex in both children and adults with ADHD 34 . Unfortunately, the study by Hoogman and colleagues 27 did not investigate case-control differences in regional cortical volumes, and thus these cannot be excluded in adults 27 . In line with this observation, a past study from our group suggested that anatomical connectivity among fronto-parietal cortical regions—but not fronto-striatal connectivity—was associated with treatment response in adults with ADHD 35 . Finally, there is preliminary evidence that biological factors implicated in treatment response may at least partly differ from those underlying differences between ADHD and neurotypical controls 20 , 36 . Unfortunately, anatomical studies comparing responders and non-responders so far: (1) include only children, or a mixed sample of children and adults; (2) did not include neurotypical controls for comparison; and (3) have mostly been based on volumetric measures. Cortical volume (CV) is a product of two distinct parameters, cortical thickness (CT) and surface area (SA), that, in turn, have distinct genetic and developmental origins 37 , 38 . However, no study has yet investigated the relationship between regional differences in CV, SA and CT, and adult treatment outcome. Hence, it remains unclear what the brain anatomical associates of adult treatment response are, whether these involve surface-based cortical measures, and how these relate to potential underpinning cellular mechanisms.

To address these questions, this prospective study uses structural MRI to first compare CV, CT and SA in adult neurotypical controls and adults with ADHD, and then separately in ADHD responders and non-responders to two months of MPH treatment. It also tested whether differences between responders and non-responders were associated with improvement on inattentive and/or hyperactive-impulsive symptoms. Finally, we performed a virtual histology analysis to aid interpretation of the group morphometric differences. Specifically, following a previously published approach 39 , 40 , we tested whether regional group differences were enriched for genes involved in MPH pharmacodynamics or expressed by different brain cell types.

The sample included 60 adults with ADHD and 23 matched neurotypical controls. At follow-up, 42 individuals with ADHD were identified as responders and 18 as non-responders to MPH. The two subgroups did not significantly differ in clinical presentation, baseline severity and MPH dose at follow-up (refer to page 2 of the Supplementary Information ). All of the participants were included in the following analyses.

Structural MRI analysis

Global brain measures.

Non-responders had significantly lower total intracranial volume ( t  = 2.51, P  = 0.015) and mean SA ( t  = 3.146, P  = 0.003) than responders. We did not observe other significant group differences (Supplementary Table 1 ).

Vertex-wise comparison between ADHD and controls

When compared with the controls, individuals with ADHD (combined responders and non-responders) had significantly smaller CV in three clusters in the left hemisphere (random field theory (RFT) P  < 0.05). These clusters included: (1) the posterior cingulate cortex, precuneus and superior parietal lobule; (2) the pars triangularis and middle/superior frontal gyri; (3) and the fusiform gyrus and inferior/middle temporal gyri (Fig. 1 and Table 1a ). Furthermore, adults with ADHD had significantly lower CT in two clusters (RFT P  < 0.05): (1) the left fusiform gyrus, temporal pole and gyri; (2) and the right supramarginal gyrus and parietal lobules (Fig. 1 and Table 1a ). No significant differences in SA were observed.

Vertex-wise comparisons between the whole ADHD group and neurotypical controls identified significant CV reductions in the ADHD group in three clusters, and lower CT in the ADHD group in two clusters. Compared with ADHD responders, ADHD non-responders had significant reductions in CV across five clusters and significantly lower cortical SA in a further five clusters. For each contrast, uncorrected t -maps of effects are shown on the left, cluster maps after RFT correction are shown on the right. Cluster coordinates are reported in Table 1a,b .

Vertex-wise comparison between responders and non-responders

Non-responders showed much smaller CV across five clusters (RFT P  < 0.05) than ADHD treatment responders. These clusters included: (1) the left temporo-parietal-insular regions; (2) the right precuneus and parietal lobules; (3) the right orbitofrontal cortex and middle frontal gyrus; (4) the right insula, temporal pole and middle/superior temporal gyri; and (5) the fusiform, lingual and parahippocampal gyri, and occipital cortex (Fig. 1 and Table 1b ). Non-responders also had significantly lower cortical SA (RFT P  < 0.05) in five clusters partially overlapping with those showing significant group differences in CV. These included the right fronto-parietal and temporal regions, and the left temporal, occipital and parietal regions (Fig. 1 and Table 1b ). No significant differences in CT were observed between responders and non-responders.

Secondary statistical analysis

Subgroup comparisons.

We first considered cortical regions that significantly differed between the whole ADHD group and controls. To determine the separate contribution of the ADHD subgroups to these significant differences, we used independent-sample t -tests to compare morphometric measures in the above five clusters between controls, and (separately) between responders and non-responders. We observed that both ADHD non-responders and responders showed significantly lower CV and CT than the controls in these five clusters. The two clinical groups only significantly differed in the volume of cluster 3 (that is, the left fusiform gyrus and inferior/middle temporal gyri), which was smaller in non-responders ( t  = −2.337, P  = 0.023; Fig. 2 and Supplementary Table 2 ).

a , b , Subgroup comparisons for CV ( a ) and CT ( b ). Both responders and non-responders significantly differed from the controls in all of the five clusters that were significantly different between the whole ADHD sample and controls. Furthermore, non-responders had lower CV in cluster 3 (that is, the left fusiform gyrus and inferior and middle temporal gyri) than responders. Individual participants’ data plotted as dots. Bounds of upper and lower whiskers represent maxima and minima, respectively; the center boxes represents the interquartile range, with the median represented by the middle horizontal lines. Significance: * P  < 0.05; ** P  < 0.01; *** P  < 0.001. Full statistical results are reported in Supplementary Table 2 . Con, controls; Nre, non-responders; Re, responders.

We then considered the cortical regions that significantly differed between responders and non-responders. Independent-sample t -tests revealed no differences in these ten clusters between ADHD responders and controls; however, significant differences in CV and SA were noted between non-responders and controls in all ten clusters (Fig. 3 and Supplementary Table 3 ).

Only non-responders significantly differed from the controls in the ten clusters significantly different between ADHD responders and non-responders. Responders did not significantly differ from controls in these clusters. a , b , Display comparisons for CV ( a ) and SA ( b ). Individual participants’ data plotted as dots. Significance: * P  < 0.05; ** P  < 0.01; *** P  < 0.001. Full statistical results are reported in Supplementary Table 3 .

Associations with symptom improvement

We used linear regression to determine whether the observed cortical differences between ADHD treatment responders and non-responders were associated with individual improvement on either inattentive or hyperactive-impulsive symptoms after two months of treatment. After correcting for multiple comparisons ( P  ≤ 0.005), out of the ten clusters in which significant differences between responders and non-responders were observed, one-fifth of the volumetric and three-fifths of the SA clusters showed significant positive associations with improvement on inattentive symptoms (Fig. 4 and Supplementary Table 4 ).

After correcting for multiple comparisons, the morphometric differences between responders ( N  = 42) and non-responders ( N  = 18) in four clusters were significantly associated with an improvement on inattentive symptoms at two months. Full statistical results are reported in Supplementary Table 4 . BAARS-ina, Barkley-inattentive score.

Genomic analyses (virtual histology)

Finally, we investigated the genomic associates of the observed morphometric differences between individuals with ADHD and neurotypical controls, and between ADHD responders and non-responders to MPH. Differences in CT between the whole ADHD group and controls were enriched for genes associated with noradrenaline transport (CT odds ratio (OR) = 13.012, pFDR = 0.028), and for genes expressed by astrocytes (CT OR = 2.93, pFDR = 0.014). We did not observe any significant enrichment of the cortical differences between responders and non-responders. See Supplementary Figs. 1 and 2 , and Supplementary Tables 5 and 6 for the complete results.

Compared with neurotypical controls, individuals with ADHD (responders and non-responders combined) had significantly smaller CV in the left fronto-temporo-parietal regions, and CT in the left temporal and right parietal regions. These group differences were driven by both ADHD treatment responders and non-responders, although the latter had more prominent temporo-occipital volumetric alterations. When directly compared, non-responders exhibited lower total and regional CV and SA than responders, especially in fronto-temporal regions; however, only the former significantly differed from the controls in these measures, and only the volumetric differences in the left temporo-occipital cortex partially overlapped with those observed in the ADHD versus controls comparison. Thus, non-responders had more pronounced volumetric differences and additional morphometric alterations not related to an ADHD diagnosis per se than responders.

The fact that the identified cortical areas are related to lower treatment response is in line with their role in supporting brain functions implicated in ADHD. For instance, the superior and inferior parietal cortices are part of the dorsal and ventral fronto-parietal networks, which support attentive functions 41 , 42 . The right middle prefrontal cortex is also important to reorient attention to relevant stimuli 43 , whereas the orbitofrontal cortex—together with anterior temporal regions—has been related to decision-making, emotion regulation and reward processing 44 , 45 , 46 . The inferior and middle temporal gyri are involved in several cognitive processes, including memory, visual perception and multimodal integration 47 . Furthermore, these brain regions have been implicated in functional MRI studies. For instance, functional MRI meta-analyses have identified consistently reduced activation in fronto-parietal areas during response inhibition, attention, and timing in adults and children with ADHD compared with controls 48 , 49 . Finally, there is evidence that MPH modulates the activity of these brain areas. For example, past meta-analyses reported upregulation of fronto-parieto-temporo-occipital areas during cognitive tasks after MPH administration in youths with ADHD 50 , 51 . In summary, the observed fronto-parieto-temporo-occipital morphometric differences between responders and non-responders are in line with the functional roles of the identified regions and the modulatory action of MPH.

This work adds to past findings from structural MRI studies. These have mostly focused on comparisons between ADHD and neurotypical individuals, and have reported reduced total and regional cortico-subcortical volumes, especially in children with ADHD 26 . However, heterogeneity exists even in adults, and neuroanatomical alterations have been associated with ADHD persistence and co-morbidities 30 , 31 . We observed that morphometric heterogeneity is also associated with variation in treatment response. Past structural MRI studies comparing ADHD responders and non-responders to treatment are limited. One such recent study in a mixed pediatric and adult sample reported reduced left putamen and increased bilateral precuneus volumes in non-responders compared with responders, and that these (and additional volumetric differences in fronto-parieto-occipital cortical regions) could differentiate between responders and non-responders using a machine learning approach 33 . These cortical areas partially overlap with those identified in our study, albeit we did not observe regions of increased volume. Inconsistencies may be related to differences in both the sample and study characteristics. For instance, they included both children and adults, but increasing age is associated with less evident volumetric alterations 24 , 25 , 27 , 28 . Further, in this previous retrospective study, individuals with ADHD were classified as responders or non-responders on the basis of a global clinical improvement after a variable treatment duration, whereas, in our prospective interventional study, we classified individuals with ADHD as responders or non-responders on the basis of an ADHD symptom scale after a fixed period of treatment (two months). Our results add to these previous findings, as we observed that differences in cortical structure between responders and non-responders were associated with variation in improvement on inattentive symptoms.

Finally, to aid the interpretation of the observed morphometric group differences, we used a virtual histology approach to map our neuroanatomical results to putative biological processes involved in MPH pharmacodynamics and brain cell types. This exploratory analysis built on previous work showing that morphometric measures rely on different developmental processes 37 , 38 , which, in turn, are regulated by a complex gene–environment interplay 52 , 53 , 54 . We observed that ADHD versus controls differences in CT were enriched for genes involved in the transport of noradrenaline. These preliminary results corroborate previous evidence that links noradrenaline dysregulation to ADHD pathophysiology, and that substantiates the therapeutic use of MPH 55 . Animal studies suggest that negative early life events may impact on brain development partly through disrupting noradrenaline signaling 56 . For instance, exposure to nicotine during pregnancy, which is a known risk factor for ADHD 57 , has been associated with increased levels of cortical noradrenaline in infant mice 58 . Furthermore, animal studies suggested that therapeutic doses of stimulants mainly affect catecholamine levels at a cortical level, and especially those of NA 4 , 59 . Taken together, our current work and previous findings suggest that variation in noradrenaline transport may contribute to altered brain development and heterogeneity in the treatment response.

We also observed an enrichment for genes expressed by astrocytes. These are glial cells that contribute to neurotransmitter homeostasis, synaptic development and modulation, and the blood brain barrier 60 . Astrocyte integrity is also required to support myelination during development 61 . Accordingly, alterations to astrocytes may hinder myelination and affect white matter tract development. In line with this, meta-analyses of diffusion imaging studies have identified several brain connectivity alterations in individuals with ADHD, especially in the splenium and body of the corpus callosum, which connect posterior cortical areas such as those identified in this structural analysis 62 . Thus, altered astrocyte development might potentially represent a shared mechanism underlying both grey and white matter pathology in ADHD. Furthermore, as they support optimal synaptic functioning, an alteration at this level may potentially contribute to lower treatment response to MPH. In summary, our virtual histology approach suggested that differences in CT between ADHD and controls were enriched for genes involved in noradrenaline transport and expressed by astrocytes. Further studies are needed to elucidate the biological pathways linking variation in genomic expression to neuroanatomy and this to treatment response. For instance, the single nucleotide polymorphism rs28386840 of the SLC6A2 gene has been associated with increased noradrenaline transporter binding in the thalamus of individuals with ADHD compared with that of controls 63 , and also with response to MPH in a meta-analysis 15 . Unfortunately, this variant was not tested in the only imaging genetic study investigating the relationship between SLC6A2 polymorphism and cerebral volume or thickness 64 , but it warrants further investigation.

This study has several strengths. We specifically investigated the morphometric differences between responders and non-responders to MPH in a sample of adults with ADHD. The interventional study design allowed us to overcome limitations of naturalistic studies in ADHD, which mainly include patients on treatment and thus are enriched in responders. The study also benefitted from the homogeneity in treatment formulation and duration; the inclusion of controls for comparative analyses; and the investigation of both volumetric and surface-based cortical differences. However, limitations should be taken into consideration. We included a small percentage of individuals with ADHD who had previously been exposed to medication. Previous exposure to medication has been suggested to have a normalizing effect on brain structure 24 , although other reports suggest that this may not be the case 65 . Our findings suggest that the observed normalizing effect of long-term treatment on brain anatomy may be at least in part dependent on a selection bias, as responders to treatment have less severe/fewer pre-treatment brain alterations. We only recruited males because ADHD is more commonly diagnosed in males 66 , and there is preliminary evidence of sex differences in brain anatomy and biological response to stimulants 67 , 68 , 69 . Further, it is not known whether sex differences in brain morphometry may relate to sex differences in treatment response. We therefore only included males to avoid potential sex-related confounding on our morphometric analyses. Nonetheless, we encourage future studies to extend our analyses to the female population with ADHD. Similarly, we only included participants without current co-morbid disorders because there is evidence that differences in neuroanatomy exist between individuals with/without co-morbidities 70 . However, our results should be validated in clinical samples also including participants with co-morbidities. Furthermore, we focused our analyses on cortical morphometric characteristics. We made this choice because a previous structural connectivity study from our group identified cortico-cortical but not fronto-striatal anatomical characteristics related to treatment response in adult ADHD 35 . This is also in line with prior meta-analytic studies showing that increasing age was associated with less evident structural abnormalities in the basal ganglia 24 , 25 . Nevertheless, future studies would benefit from investigating subcortical regions in relation to adult treatment response. Moreover, although we recruited a relatively large sample of adults with ADHD and included controls for comparative analyses, findings need to be validated in larger samples to ensure generalizability. For instance, our prospective study identified a limited number of non-responders ( N  = 18). The observed proportion of non-responders is in line with previous randomized clinical trials 11 and thus representative of the actual ADHD clinical population. However, the small sample size together with the limited number of genes identified during the coding phase may have limited our power to explore genetic enrichment within ADHD subgroups. Furthermore, despite offering a unique opportunity to map neuroanatomy to neurobiology, virtual histology approaches remain limited in their spatial coverage and resolution (especially compared with structural MRI data). Consequently, future studies should validate our analysis once high-resolution gene expression datasets become available and in larger samples. We considered a two-month follow-up as this is the median duration of randomized controlled trials of extended-release MPH in adults with ADHD 71 . This timeframe is usually sufficient for dose optimization, nevertheless, studies with longer follow-ups are encouraged. They may also clarify how treatment-related changes may be potentially related to varying response over time. Finally, we established associations between brain anatomical characteristics and known genetic expression maps, however, future longitudinal imaging genetic studies are needed to clarify potential causal mechanisms.

We provide evidence that adults with ADHD who do not respond to MPH have significant differences in cortical morphometry compared with those who respond. Responders and non-responders may therefore represent different biological subgroups within the heterogenous population with ADHD. Further, ADHD versus control group differences in cortical regions were enriched for genes expressed by astrocytes and involved in the transport of noradrenaline. Parsing neuroanatomic heterogeneity is critically important to better understand the mechanisms underlying variation in clinical presentation and outcome 31 . These results need to be replicated and extended in independent samples and, preferably, confirmed by meta-analyses 72 . In the future, this knowledge may help advance the development of clinical interventions, for example, by identifying treatment resistant individuals in the context of clinical trials of new treatments.

Sample and research protocol

This study is part of a single-blind placebo-controlled cross-over study, followed by a longitudinal open-label phase (NCT 03709940), which was conducted at the South London and Maudsley NHS Foundation Trust (United Kingdom). Details on the sample and study protocol (NCT 03709940) have been described in a previous work 35 . In this report we focused on the structural MRI data. We included 60 participants with a clinical diagnosis of ADHD according to the DSM-5 criteria 73 , aged 18–45 years, with no current co-morbid disorders, and a full-scale IQ of above 70. The sample size was determined based on a power calculation ( Supplementary Information ). Attention deficit hyperactivity disorder is more commonly diagnosed in males 66 , and there is preliminary evidence of sex differences in brain morphometry and biological response to stimulants 67 , 68 , 69 , we therefore only included males to enhance sample homogeneity (see the 'Discussion' section for potential limitations). Recruitment focused on the inclusion of medication-naive adults, but we also included a small minority of individuals who were previously medicated and had stopped treatment at least one year before the start of the study (see the 'Results' section). The severity of the symptoms was measured at the baseline and also at follow-up using BAARS-IV 74 , which provided three scores (ADHD total score, ADHD inattention and ADHD hyperactivity-impulsivity). IQ was measured using the Wechsler Abbreviated Scale of Intelligence 75 , whereas handedness was measured using a modified version of the Edinburgh Handedness Inventory 76 .

Participants with ADHD completed MRI scanning before starting routine treatment with the same long-acting formulation of MPH (Concerta XL, titrated up to 54 mg). During titration, side effects were monitored, and the dose was adjusted if needed. The dose was considered as a co-variate. Treatment response was measured at two months. According to previously published criteria, we used a categorical definition of treatment response based on a symptomatic improvement of at least 30%, as measured by the BAARS-IV total score at follow-up as compared with the baseline 11 , 77 . We identified a subgroup with a high average and a subgroup with a low average treatment response, which we labelled as responders and non-responders, respectively. We also included 23 neurotypical adults matched for sex, age and IQ for comparative analyses. All participants gave written informed consent. We assert that all procedures contributing to this work comply with the ethical standards of the relevant national and institutional committees on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008. Participants received £50 after the scanning sessions as a compensation for their time. Ethical approval was obtained by Camden and Islington Research Ethics Committee (12/LO/0630).

Structural MRI data acquisition and analysis

Mri acquisition parameters.

High-resolution T 1 -weighted structural images were acquired on a 3 T MR750 GE scanner (General Electric, Milwaukee) for each patient with the following parameters: 196 slices, 1.2 mm thickness with 1.2 mm gap, repetition time (TR) = 7.312 ms, time to echo (TE) = 3.016 ms and flip angle = 11°.

Cortical reconstruction using FreeSurfer

FreeSurfer v.5.3.0 software 78 was used to derive tessellated models of the cortical surface for each T 1 -weighted image. These well-validated and fully automated procedures have been extensively described elsewhere 79 , 80 , 81 , 82 , 83 . Resulting surface models were visually inspected for reconstruction errors. Surface reconstructions with visible inaccuracies were further excluded from the statistical analysis and are not described in this study. Three separate vertex based morphometric cortical features were calculated from the individual surface reconstructions: (1) the cortical volume, which is composed of (2) CT 83 and (3) pial SA 84 . Before further analysis, all features were smoothed using a 15 mm surface-based full-width at half-maximum Gaussian kernel.

Vertex-wise between-group comparison of cortical measures

Vertex-wise statistical analyses of each cortical feature were conducted using the SurfStat toolbox 85 for MATLAB (R2014a, The Mathworks).

For the comparisons between the controls and participants with ADHD, parameter estimates were obtained by regression of a generalised liner model at each vertex i , with age as a continuous co-variate, that is,

where ε i is the residual error.

To examine differences between ADHD treatment responders and non-responders in each morphometric measure, we also included age, full-scale IQ, BAARS-IV baseline total score, MPH dose and weight as continuous co-variates, and handedness as a categorical variable, that is,

where ε i is the residual error. Effects of interest were estimated from coefficient β 1 -normalized by the corresponding standard error. Co-variates were selected as previously associated with treatment response 35 . Corrections for multiple comparisons were performed using a RFT-based cluster analysis for non-isotropic images at a cluster-threshold of P  < 0.05 (two-tailed) 86 . Imaging files are publicly available on OSF ( https://osf.io/mw4y3/ ).

To test whether significant vertex-wise differences between the whole ADHD group and controls were driven by either responders or non-responders (or both), we ran independent-sample t -tests (two-tailed) using SPSS (v28, IBM) and compared the morphometric measures in the identified clusters separately between controls and responders, and between controls and non-responders. For completeness, we also compared CT, CV and SA between clinical subgroups. Similarly, where we observed significant vertex-wise differences between responders and non-responders, we ran independent sample t -tests to compare morphometric measures in these identified clusters separately between responders and controls and non-responders and controls. We considered these secondary analyses significant at P  < 0.05.

We ran linear regressions to determine whether differences between responders and non-responders were associated with individual improvement on either inattentive or hyperactive-impulsive symptoms. Morphometric measures were the independent variables, whereas the BAARS-IV inattentive and hyperactive-impulsive scores at follow-up, as compared with the baseline, were the dependent variables. We applied Bonferroni correction for multiple comparisons (number of clusters = 10, P  ≤ 0.005).

Finally, we conducted an exploratory analysis to map our neuroanatomical results to putative biological processes and cell-types involved in MPH treatment response and brain development. This analysis included two steps: decoding and enrichment.

First, we identified those genes whose spatial expression was significantly similar to our neuroanatomical patterns of interest (neuroanatomical differences between the participants with ADHD and the controls, and between the responders and non-responders). Following a previously published approach 39 , 40 , we leveraged the Allen Human Brain Atlas of gene expression 87 , which is currently the most comprehensive publicly available atlas of gene-expression in the brain, and Neurovault ( https://neurovault.org ), a Python code embedded within Neurovault and Neurosynth ( https://neurosynth.org ).

Next we tested how the resulting genes were enriched for: (1) genes previously linked to the regulation of the metabolism and signaling of key neurotransmitters potentially involved in MPH pharmacodynamics; and (2) genes expressed in brain cell types during development.

Specifically, in line with the mechanism of action of MPH, we focused on genes involved in the synthesis and degradation of dopamine and noradrenaline, as well as their receptors and transporters 55 . We also included genes expressed within serotoninergic pathways, as there is some evidence that MPH may also bind the 5-HT1A receptor; however, its biological significance is unclear 88 . Finally, we tested genes regulating nitric oxide signaling, which has been suggested to be affected by MPH treatment 89 . The tested genes were based on gene-set annotations listed in the human gene ontology database ( http://www.gsea-msigdb.org/ ) 90 . The gene list overlap was computed using a specific R (v.4.3) code written by M.V. Lombardo ( github.com/mvlombardo/utils/blob/master/genelistOverlap.R ) 39 .

Finally, due to the developmental nature of ADHD, we explored if the identified genes overlapped with those expressed by brain cell types during development, including progenitor cells, microglia, astrocytes and neuronal cells (excitatory and inhibitory). The cell type-specific gene lists were based on a past work 91 and are available at ( http://www.gsea-msigdb.org/ ). We corrected each of these enrichment analyses for multiple comparisons across all contrasts and gene sets ( P FDR  < 0.05).

Reporting summary

Further information on research design is available in the Nature Portfolio Reporting Summary linked to this article.

Data availability

Imaging files are publicly available via OSF at https://doi.org/10.17605/OSF.IO/MW4Y3 (ref. 92 ).

Code availability

Magnetic resonance imaging data analysis was performed using the FreeSurfer v.5.3.0 software 78 , which was used to derive tessellated models of the cortical surface for each T1-weighted image. Vertex-wise statistical analyses of each cortical feature were conducted using the SurfStat toolbox 92 for MATLAB (R2014a, The Mathworks). Following a previously published approach 39 , 40 , we leveraged the Allen Human Brain Atlas (AHBA) of gene expression 87 , currently the most comprehensive publicly available atlas of gene-expression in the brain, and Neurovault ( https://neurovault.org ), a Python code embedded within Neurovault and Neurosynth ( https://neurosynth.org ), for decoding. For the enrichment analysis, the tested genes were based on gene-set annotations listed in the human gene ontology database ( http://www.gsea-msigdb.org/ ) 90 ; the gene list overlap was computed using a specific R (v.4.3) code written by M.V. Lombardo ( github.com/mvlombardo/utils/blob/master/genelistOverlap.R ) 39 , 40 .

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Acknowledgements

This research project was funded by Shire (project no. IST-ALB-000217 to D.G.M.) and included support from the NIHR Maudsley Biomedical Research Centre. Further, D.G.M. was funded by two IMI initiatives (EU AIMS and AIMS-2-TRIALS) under grant agreement nos.115300 and 777394. The design of the study, data collection and analysis, and decision to publish were not influenced by the funding bodies. We thank all of the study participants, the Pharmacy Team and the Adult ADHD Clinic at the Maudsley Hospital (London, UK). We thank A. Hye and M. Metha (King’s College London) for their support. We greatly appreciate M.V. Lombardo’s input as he wrote the code used in the enrichment analysis. We would like to thank the Department of Forensic and Neurodevelopmental Sciences, King’s College London, for helpful discussion.

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These authors contributed equally: V. Parlatini, D. S. Andrews.

Authors and Affiliations

Institute of Translational Neurodevelopment, Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK

V. Parlatini, D. S. Andrews, C. M. Pretzsch, M. Arenella, E. Daly & D. G. Murphy

Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK

School of Psychology, University of Southampton, Southampton, UK

V. Parlatini, C. M. Pretzsch, M. Arenella, E. Daly & D. G. Murphy

Solent NHS Trust, Southampton, UK

V. Parlatini

Department of Psychiatry and Behavioral Sciences, The M.I.N.D Institute, University of California Davis, Sacramento, CA, USA

D. S. Andrews

Department of Child and Adolescent Psychiatry, Goethe-University Frankfurt, Frankfurt am Main, Germany

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All of the authors made a substantial contribution to the study. V.P. was responsible for the recruitment of participants, data acquisition and analysis, and writing the paper. D.S.A. was responsible for the data analysis and writing. C.M.P. and M.A. were responsible for the genomic analysis and writing. E.D. and C.E. contributed to study design and supervision. D.G.M. contributed to study design, supervision and critical revision of the paper.

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D.M. was funded by two IMI initiatives (EU AIMS and AIMS-2-TRIALS) under grant agreement nos.115300 and 777394. The other authors have no conflicts of interest to declare.

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Parlatini, V., Andrews, D.S., Pretzsch, C.M. et al. Cortical alterations associated with lower response to methylphenidate in adults with ADHD. Nat. Mental Health (2024). https://doi.org/10.1038/s44220-024-00228-y

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• According to the Intergovernmental Panel on Climate Change ( IPCC ), "Since systematic scientific assessments began in the 1970s, the influence of human activity on the warming of the climate system has evolved from theory to established fact." 1
• Scientific information taken from natural sources (such as ice cores, rocks, and tree rings) and from modern equipment (like satellites and instruments) all show the signs of a changing climate.
• From global temperature rise to melting ice sheets, the evidence of a warming planet abounds.

The rate of change since the mid-20th century is unprecedented over millennia.

Earth's climate has changed throughout history. Just in the last 800,000 years, there have been eight cycles of ice ages and warmer periods, with the end of the last ice age about 11,700 years ago marking the beginning of the modern climate era — and of human civilization. Most of these climate changes are attributed to very small variations in Earth’s orbit that change the amount of solar energy our planet receives.

The current warming trend is different because it is clearly the result of human activities since the mid-1800s, and is proceeding at a rate not seen over many recent millennia. 1 It is undeniable that human activities have produced the atmospheric gases that have trapped more of the Sun’s energy in the Earth system. This extra energy has warmed the atmosphere, ocean, and land, and widespread and rapid changes in the atmosphere, ocean, cryosphere, and biosphere have occurred.

Earth-orbiting satellites and new technologies have helped scientists see the big picture, collecting many different types of information about our planet and its climate all over the world. These data, collected over many years, reveal the signs and patterns of a changing climate.

Scientists demonstrated the heat-trapping nature of carbon dioxide and other gases in the mid-19th century. 2 Many of the science instruments NASA uses to study our climate focus on how these gases affect the movement of infrared radiation through the atmosphere. From the measured impacts of increases in these gases, there is no question that increased greenhouse gas levels warm Earth in response.

Scientific evidence for warming of the climate system is unequivocal.

Intergovernmental Panel on Climate Change

Ice cores drawn from Greenland, Antarctica, and tropical mountain glaciers show that Earth’s climate responds to changes in greenhouse gas levels. Ancient evidence can also be found in tree rings, ocean sediments, coral reefs, and layers of sedimentary rocks. This ancient, or paleoclimate, evidence reveals that current warming is occurring roughly 10 times faster than the average rate of warming after an ice age. Carbon dioxide from human activities is increasing about 250 times faster than it did from natural sources after the last Ice Age. 3

The Evidence for Rapid Climate Change Is Compelling:

Global Temperature Is Rising

The planet's average surface temperature has risen about 2 degrees Fahrenheit (1 degrees Celsius) since the late 19th century, a change driven largely by increased carbon dioxide emissions into the atmosphere and other human activities. 4 Most of the warming occurred in the past 40 years, with the seven most recent years being the warmest. The years 2016 and 2020 are tied for the warmest year on record. 5 Image credit: Ashwin Kumar, Creative Commons Attribution-Share Alike 2.0 Generic.

The Ocean Is Getting Warmer

The ocean has absorbed much of this increased heat, with the top 100 meters (about 328 feet) of ocean showing warming of 0.67 degrees Fahrenheit (0.33 degrees Celsius) since 1969. 6 Earth stores 90% of the extra energy in the ocean. Image credit: Kelsey Roberts/USGS

The Ice Sheets Are Shrinking

The Greenland and Antarctic ice sheets have decreased in mass. Data from NASA's Gravity Recovery and Climate Experiment show Greenland lost an average of 279 billion tons of ice per year between 1993 and 2019, while Antarctica lost about 148 billion tons of ice per year. 7 Image: The Antarctic Peninsula, Credit: NASA

Glaciers Are Retreating

Glaciers are retreating almost everywhere around the world — including in the Alps, Himalayas, Andes, Rockies, Alaska, and Africa. 8 Image: Miles Glacier, Alaska Image credit: NASA

Snow Cover Is Decreasing

Satellite observations reveal that the amount of spring snow cover in the Northern Hemisphere has decreased over the past five decades and the snow is melting earlier. 9 Image credit: NASA/JPL-Caltech

Sea Level Is Rising

Global sea level rose about 8 inches (20 centimeters) in the last century. The rate in the last two decades, however, is nearly double that of the last century and accelerating slightly every year. 10 Image credit: U.S. Army Corps of Engineers Norfolk District

Arctic Sea Ice Is Declining

Both the extent and thickness of Arctic sea ice has declined rapidly over the last several decades. 11 Credit: NASA's Scientific Visualization Studio

Extreme Events Are Increasing in Frequency

The number of record high temperature events in the United States has been increasing, while the number of record low temperature events has been decreasing, since 1950. The U.S. has also witnessed increasing numbers of intense rainfall events. 12 Image credit: Régine Fabri,  CC BY-SA 4.0 , via Wikimedia Commons

Ocean Acidification Is Increasing

Since the beginning of the Industrial Revolution, the acidity of surface ocean waters has increased by about 30%. 13 , 14 This increase is due to humans emitting more carbon dioxide into the atmosphere and hence more being absorbed into the ocean. The ocean has absorbed between 20% and 30% of total anthropogenic carbon dioxide emissions in recent decades (7.2 to 10.8 billion metric tons per year). 1 5 , 16 Image credit: NOAA

1. IPCC Sixth Assessment Report, WGI, Technical Summary . B.D. Santer et.al., “A search for human influences on the thermal structure of the atmosphere.” Nature 382 (04 July 1996): 39-46. https://doi.org/10.1038/382039a0. Gabriele C. Hegerl et al., “Detecting Greenhouse-Gas-Induced Climate Change with an Optimal Fingerprint Method.” Journal of Climate 9 (October 1996): 2281-2306. https://doi.org/10.1175/1520-0442(1996)009<2281:DGGICC>2.0.CO;2. V. Ramaswamy, et al., “Anthropogenic and Natural Influences in the Evolution of Lower Stratospheric Cooling.” Science 311 (24 February 2006): 1138-1141. https://doi.org/10.1126/science.1122587. B.D. Santer et al., “Contributions of Anthropogenic and Natural Forcing to Recent Tropopause Height Changes.” Science 301 (25 July 2003): 479-483. https://doi.org/10.1126/science.1084123. T. Westerhold et al., "An astronomically dated record of Earth’s climate and its predictability over the last 66 million years." Science 369 (11 Sept. 2020): 1383-1387. https://doi.org/10.1126/science.1094123

2. In 1824, Joseph Fourier calculated that an Earth-sized planet, at our distance from the Sun, ought to be much colder. He suggested something in the atmosphere must be acting like an insulating blanket. In 1856, Eunice Foote discovered that blanket, showing that carbon dioxide and water vapor in Earth's atmosphere trap escaping infrared (heat) radiation. In the 1860s, physicist John Tyndall recognized Earth's natural greenhouse effect and suggested that slight changes in the atmospheric composition could bring about climatic variations. In 1896, a seminal paper by Swedish scientist Svante Arrhenius first predicted that changes in atmospheric carbon dioxide levels could substantially alter the surface temperature through the greenhouse effect. In 1938, Guy Callendar connected carbon dioxide increases in Earth’s atmosphere to global warming. In 1941, Milutin Milankovic linked ice ages to Earth’s orbital characteristics. Gilbert Plass formulated the Carbon Dioxide Theory of Climate Change in 1956.

3. IPCC Sixth Assessment Report, WG1, Chapter 2 Vostok ice core data; NOAA Mauna Loa CO2 record O. Gaffney, W. Steffen, "The Anthropocene Equation." The Anthropocene Review 4, issue 1 (April 2017): 53-61. https://doi.org/abs/10.1177/2053019616688022.

4. https://www.ncei.noaa.gov/monitoring https://crudata.uea.ac.uk/cru/data/temperature/ http://data.giss.nasa.gov/gistemp

5. https://www.giss.nasa.gov/research/news/20170118/

6. S. Levitus, J. Antonov, T. Boyer, O Baranova, H. Garcia, R. Locarnini, A. Mishonov, J. Reagan, D. Seidov, E. Yarosh, M. Zweng, " NCEI ocean heat content, temperature anomalies, salinity anomalies, thermosteric sea level anomalies, halosteric sea level anomalies, and total steric sea level anomalies from 1955 to present calculated from in situ oceanographic subsurface profile data (NCEI Accession 0164586), Version 4.4. (2017) NOAA National Centers for Environmental Information. https://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/index3.html K. von Schuckmann, L. Cheng, L,. D. Palmer, J. Hansen, C. Tassone, V. Aich, S. Adusumilli, H. Beltrami, H., T. Boyer, F. Cuesta-Valero, D. Desbruyeres, C. Domingues, A. Garcia-Garcia, P. Gentine, J. Gilson, M. Gorfer, L. Haimberger, M. Ishii, M., G. Johnson, R. Killick, B. King, G. Kirchengast, N. Kolodziejczyk, J. Lyman, B. Marzeion, M. Mayer, M. Monier, D. Monselesan, S. Purkey, D. Roemmich, A. Schweiger, S. Seneviratne, A. Shepherd, D. Slater, A. Steiner, F. Straneo, M.L. Timmermans, S. Wijffels. "Heat stored in the Earth system: where does the energy go?" Earth System Science Data 12, Issue 3 (07 September 2020): 2013-2041. https://doi.org/10.5194/essd-12-2013-2020.

7. I. Velicogna, Yara Mohajerani, A. Geruo, F. Landerer, J. Mouginot, B. Noel, E. Rignot, T. Sutterly, M. van den Broeke, M. Wessem, D. Wiese, "Continuity of Ice Sheet Mass Loss in Greenland and Antarctica From the GRACE and GRACE Follow-On Missions." Geophysical Research Letters 47, Issue 8 (28 April 2020): e2020GL087291. https://doi.org/10.1029/2020GL087291.

8. National Snow and Ice Data Center World Glacier Monitoring Service

9. National Snow and Ice Data Center D.A. Robinson, D. K. Hall, and T. L. Mote, "MEaSUREs Northern Hemisphere Terrestrial Snow Cover Extent Daily 25km EASE-Grid 2.0, Version 1 (2017). Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: https://doi.org/10.5067/MEASURES/CRYOSPHERE/nsidc-0530.001 . http://nsidc.org/cryosphere/sotc/snow_extent.html Rutgers University Global Snow Lab. Data History

10. R.S. Nerem, B.D. Beckley, J. T. Fasullo, B.D. Hamlington, D. Masters, and G.T. Mitchum, "Climate-change–driven accelerated sea-level rise detected in the altimeter era." PNAS 15, no. 9 (12 Feb. 2018): 2022-2025. https://doi.org/10.1073/pnas.1717312115.

11. https://nsidc.org/cryosphere/sotc/sea_ice.html Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS, Zhang and Rothrock, 2003) http://psc.apl.washington.edu/research/projects/arctic-sea-ice-volume-anomaly/ http://psc.apl.uw.edu/research/projects/projections-of-an-ice-diminished-arctic-ocean/

12. USGCRP, 2017: Climate Science Special Report: Fourth National Climate Assessment, Volume I [Wuebbles, D.J., D.W. Fahey, K.A. Hibbard, D.J. Dokken, B.C. Stewart, and T.K. Maycock (eds.)]. U.S. Global Change Research Program, Washington, DC, USA, 470 pp, https://doi.org/10.7930/j0j964j6 .

13. http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F

14. http://www.pmel.noaa.gov/co2/story/Ocean+Acidification

15. C.L. Sabine, et al., “The Oceanic Sink for Anthropogenic CO2.” Science 305 (16 July 2004): 367-371. https://doi.org/10.1126/science.1097403.

16. Special Report on the Ocean and Cryosphere in a Changing Climate , Technical Summary, Chapter TS.5, Changing Ocean, Marine Ecosystems, and Dependent Communities, Section 5.2.2.3. https://www.ipcc.ch/srocc/chapter/technical-summary/

Header image shows clouds imitating mountains as the sun sets after midnight as seen from Denali's backcountry Unit 13 on June 14, 2019. Credit: NPS/Emily Mesner Image credit in list of evidence: Ashwin Kumar, Creative Commons Attribution-Share Alike 2.0 Generic.

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