New Research

What Really Turned the Sahara Desert From a Green Oasis Into a Wasteland?

10,000 years ago, this iconic desert was unrecognizable. A new hypothesis suggests that humans may have tipped the balance

Lorraine Boissoneault

Lorraine Boissoneault

FBBY1H (1).jpg

When most people imagine an archetypal desert landscape—with its relentless sun, rippling sand and hidden oases—they often picture the Sahara. But 11,000 years ago, what we know today as the world’s largest hot desert would’ve been unrecognizable. The now-dessicated northern strip of Africa was once green and alive, pocked with lakes, rivers, grasslands and even forests. So where did all that water go?

Archaeologist David Wright has an idea: Maybe humans and their goats tipped the balance, kick-starting this dramatic ecological transformation. In a new study in the journal Frontiers in Earth Science , Wright set out to argue that humans could be the answer to a question that has plagued archaeologists and paleoecologists for years.

The Sahara has long been subject to periodic bouts of humidity and aridity. These fluctuations are caused by slight wobbles in the tilt of the Earth’s orbital axis, which in turn changes the angle at which solar radiation penetrates the atmosphere. At repeated intervals throughout Earth’s history , there’s been more energy pouring in from the sun during the West African monsoon season, and during those times—known as African Humid Periods—much more rain comes down over north Africa.

With more rain, the region gets more greenery and rivers and lakes. All this has been known for decades. But between 8,000 and 4,500 years ago, something strange happened: The transition from humid to dry happened far more rapidly in some areas than could be explained by the orbital precession alone, resulting in the Sahara Desert as we know it today. “Scientists usually call it ‘poor parameterization’ of the data,” Wright said by email. “Which is to say that we have no idea what we’re missing here—but something’s wrong.”

As Wright pored the archaeological and environmental data (mostly sediment cores and pollen records, all dated to the same time period), he noticed what seemed like a pattern. Wherever the archaeological record showed the presence of “pastoralists”—humans with their domesticated animals—there was a corresponding change in the types and variety of plants. It was as if, every time humans and their goats and cattle hopscotched across the grasslands, they had turned everything to scrub and desert in their wake.

Wright thinks this is exactly what happened. “By overgrazing the grasses, they were reducing the amount of atmospheric moisture—plants give off moisture, which produces clouds—and enhancing albedo,” Wright said. He suggests this may have triggered the end of the humid period more abruptly than can be explained by the orbital changes. These nomadic humans also may have used fire as a land management tool, which would have exacerbated the speed at which the desert took hold.

It’s important to note that the green Sahara always would’ve turned back into a desert even without humans doing anything—that’s just how Earth’s orbit works, says geologist Jessica Tierney, an associate professor of geoscience at the University of Arizona. Moreover, according to Tierney, we don’t necessarily need humans to explain the abruptness of the transition from green to desert.

Instead, the culprits might be regular old vegetation feedbacks and changes in the amount of dust. “At first you have this slow change in the Earth’s orbit,” Tierney explains. “As that’s happening, the West African monsoon is going to get a little bit weaker. Slowly you’ll degrade the landscape, switching from desert to vegetation. And then at some point you pass the tipping point where change accelerates.”

Tierney adds that it’s hard to know what triggered the cascade in the system, because everything is so closely intertwined. During the last humid period, the Sahara was filled with hunter-gatherers. As the orbit slowly changed and less rain fell, humans would have needed to domesticate animals, like cattle and goats , for sustenance. “It could be the climate was pushing people to herd cattle, or the overgrazing practices accelerated denudation [of foliage],” Tierney says. 

Which came first? It’s hard to say with evidence we have now. “The question is: How do we test this hypothesis?” she says. “How do we isolate the climatically driven changes from the role of humans? It’s a bit of a chicken and an egg problem.” Wright, too, cautions that right now we have evidence only for correlation, not causation.

But Tierney is also intrigued by Wright’s research, and agrees with him that much more research needs to be done to answer these questions.

“We need to drill down into the dried-up lake beds that are scattered around the Sahara and look at the pollen and seed data and then match that to the archaeological datasets,” Wright said. “With enough correlations, we may be able to more definitively develop a theory of why the pace of climate change at the end of the AHP doesn’t match orbital timescales and is irregular across northern Africa.”

Tierney suggests researchers could use mathematical models that compare the impact hunter-gatherers would have on the environment versus that of pastoralists herding animals. For such models it would be necessary to have some idea of how many people lived in the Sahara at the time, but Tierney is sure there were more people in the region than there are today, excepting coastal urban areas.

While the shifts between a green Sahara and a desert do constitute a type of climate change, it’s important to understand that the mechanism differs from what we think of as anthropogenic (human-made) climate change today, which is largely driven by rising levels of CO2 and other greenhouse gases. Still, that doesn’t mean these studies can’t help us understand the impact humans are having on the environment now.

“It’s definitely important,” Tierney says. “Understanding the way those feedback (loops) work could improve our ability to predict changes for vulnerable arid and semi-arid regions.”

Wright sees an even broader message in this type of study. “Humans don’t exist in ecological vacuums,” he said. “We are a keystone species and, as such, we make massive impacts on the entire ecological complexion of the Earth. Some of these can be good for us, but some have really threatened the long-term sustainability of the Earth.” 

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Lorraine Boissoneault

Lorraine Boissoneault | | READ MORE

Lorraine Boissoneault is a contributing writer to SmithsonianMag.com covering history and archaeology. She has previously written for The Atlantic, Salon, Nautilus and others. She is also the author of The Last Voyageurs: Retracing La Salle's Journey Across America. Website: http://www.lboissoneault.com/

sand dunes showing desertification of the Tibetan Plateau

Sand dunes show the increasing desertification of the Tibetan Plateau, as land dries out and vegetation cover vanishes due to human activity.

  • ENVIRONMENT

Desertification, explained

Humans are driving the transformation of drylands into desert on an unprecedented scale around the world, with serious consequences. But there are solutions.

As global temperatures rise and the human population expands, more of the planet is vulnerable to desertification, the permanent degradation of land that was once arable.

While interpretations of the term desertification vary, the concern centers on human-caused land degradation in areas with low or variable rainfall known as drylands: arid, semi-arid, and sub-humid lands . These drylands account for more than 40 percent of the world's terrestrial surface area.

While land degradation has occurred throughout history, the pace has accelerated, reaching 30 to 35 times the historical rate, according to the United Nations . This degradation tends to be driven by a number of factors, including urbanization , mining, farming, and ranching. In the course of these activities, trees and other vegetation are cleared away , animal hooves pound the dirt, and crops deplete nutrients in the soil. Climate change also plays a significant role, increasing the risk of drought .

All of this contributes to soil erosion and an inability for the land to retain water or regrow plants. About 2 billion people live on the drylands that are vulnerable to desertification, which could displace an estimated 50 million people by 2030.

Where is desertification happening, and why?

The risk of desertification is widespread and spans more than 100 countries , hitting some of the poorest and most vulnerable populations the hardest, since subsistence farming is common across many of the affected regions.

More than 75 percent of Earth's land area is already degraded, according to the European Commission's World Atlas of Desertification , and more than 90 percent could become degraded by 2050. The commission's Joint Research Centre found that a total area half of the size of the European Union (1.61 million square miles, or 4.18 million square kilometers) is degraded annually, with Africa and Asia being the most affected.

The drivers of land degradation vary with different locations, and causes often overlap with each other. In the regions of Uzbekistan and Kazakhstan surrounding the Aral Sea , excessive use of water for agricultural irrigation has been a primary culprit in causing the sea to shrink , leaving behind a saline desert. And in Africa's Sahel region , bordered by the Sahara Desert to the north and savannas to the south, population growth has caused an increase in wood harvesting, illegal farming, and land-clearing for housing, among other changes.

The prospect of climate change and warmer average temperatures could amplify these effects. The Mediterranean region would experience a drastic transformation with warming of 2 degrees Celsius, according to one study , with all of southern Spain becoming desert. Another recent study found that the same level of warming would result in "aridification," or drying out, of up to 30 percent of Earth's land surface.

a herding family in a desertified pasture

A herder family tends pastures beside a growing desert.

When land becomes desert, its ability to support surrounding populations of people and animals declines sharply. Food often doesn't grow, water can't be collected, and habitats shift. This often produces several human health problems that range from malnutrition, respiratory disease caused by dusty air, and other diseases stemming from a lack of clean water.

Desertification solutions

In 1994, the United Nations established the Convention to Combat Desertification (UNCCD), through which 122 countries have committed to Land Degradation Neutrality targets, similar to the way countries in the climate Paris Agreement have agreed to targets for reducing carbon pollution. These efforts involve working with farmers to safeguard arable land, repairing degraded land, and managing water supplies more effectively.

The UNCCD has also promoted the Great Green Wall Initiative , an effort to restore 386,000 square miles (100 million hectares) across 20 countries in Africa by 2030. A similar effort is underway in northern China , with the government planting trees along the border of the Gobi desert to prevent it from expanding as farming, livestock grazing , and urbanization , along with climate change, removed buffering vegetation.

However, the results for these types of restoration efforts so far have been mixed. One type of mesquite tree planted in East Africa to buffer against desertification has proved to be invasive and problematic . The Great Green Wall initiative in Africa has evolved away from the idea of simply planting trees and toward the idea of " re-greening ," or supporting small farmers in managing land to maximize water harvesting (via stone barriers that decrease water runoff, for example) and nurture natural regrowth of trees and vegetation.

"The absolute number of farmers in these [at-risk rural] regions is so large that even simple and inexpensive interventions can have regional impacts," write the authors of the World Atlas of Desertification, noting that more than 80 percent of the world's farms are managed by individual households, primarily in Africa and Asia. "Smallholders are now seen as part of the solution of land degradation rather than a main problem, which was a prevailing view of the past."

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Desertification

Charney's hypothesis

There is a controversy about the advance of deserts in the world (1). There is a widespread belief that the Sahara desert is advancing into the Sahel region, for instance. The Sahel is a narrow band of West Africa between 15 -18 ° N, between the Sahara to the north and savannah (grass and open forest) and equatorial forest to the south. It extends from Senegal at the coast at about 15 ° W, across Mali and Niger, to about 15 ° E. It receives rainfall during a short but active wet season, from late June to mid September. It is covered by grassland and supports a pasture-based society which traditionally moved meridionally following the rains. Its northern limit may be defined by the 200 mm/a isohyet.

Is the Sahara extending into the Sahel? And if so, is this because of fluctuations of rainfall (total amount, rainfall intensity, duration of wet season, …) or is it largely the result of human activities, such as overgrazing or the removal of trees for firewood? There are also the questions: Do deserts create droughts? Do droughts create deserts? In other words, is there a positive climate feedback, which accelerates land degradation? A now classic paper by Jules Charney in 1975 (2) speculated that overgrazing in the Sahel leads to less vegetation, which raises the ground’s albedo, so that less solar radiation is absorbed and the Earth’s surface becomes cooler. It should be noted that the atmosphere above the Sahara experiences continues radiative cooling, because the dry air, free of clouds, absorbs very little of the longwave radiation upwelling from the ground. This radiative cooling is naturally compensated by subsidence heating, and the subsidence sustains the dry air, cloudlessness, and arid surface conditions. According Charney, overgrazing would enhance the radiative loss, which would foster subsidence within the troposphere, leading to drier conditions in the Sahel, and therefore less plant growth during the wet season. Less vegetation means a higher albedo. So we have positive feedback and a self-aggravating process, culminating in desertification, a process of land degradation that destroys its productivity. Charney’s hypothesis was supported by experiments with a very simple GCM, in which he changed the surface albedo from 20% to 30% (3).

The problem of overgrazing in the Sahel is as acute now as it was in the 1960's, yet there is no clear rainfall trend in the Sahel. The period 1930-'60 was slightly wetter than 1960-'90 in most parts of the Sahel. More significant than any trend is the occurrence of dry and wet periods, each lasting several years. The Sahel enjoyed a notably wet decade in the 1950’s, which was followed by a drought in the 70’s and 80’s (1). However, land productivity was fully recovered around 1990. So Charney's hypothesis cannot be confirmed.

To reject Charney's hypothesis, one needs to examine whether the albedo has really increased in the Sahel. Satellite-estimated albedo of the Sahel between 1983-1988 was about 35% in (dry) January and 31% in (wet) July, a difference of about 4%. The seasonal variation greatly exceeded any overall change during the period. This points to there being no irreversible change towards desert. It is concluded that the formation of desert is not a single self-aggravating process, but is complex, reflecting changes of both climate and human activities. There may be incomplete recovery after a dry period, or changes in the composition of the vegetation.

Desertification trends are evaluated by means of the ‘normalised difference vegetation index’ (NDVI). This index, based on satellite data, quantifies the amount of vegetation (1). It is a figure for the ‘green-ness’ of the surface, the ratio of the measured reflectances of red light (i.e. 0.55-0.68 micron wavelength) and near-infra-red (0.73-1.1) in solar radiation. NDVI is strongly correlated with the biological productivity of an area. In the Sahel there is close agreement of the shifts of NDVI and rainfall boundaries during 1980 - 1995, i.e. the NDVI/rainfall relationship remained about constant. In other words, there was no progressive ‘march’ of desert over more fertile areas, no one-way ratchet effect due to deserts causing droughts.

A question related to the question about deserts causing drought, is that of large lakes inducing rain. Nicholson et al. (1) mentioned proposals to flood the Kalahari desert of Botswana to increase the rainfall regionally. The topic was discussed indirectly in Notes 10.I and 10.J, where reasons are given for expecting no influence of forestation on rainfall, unless done over large areas; even then, the enhanced rainfall is insufficient to support the manmade forest.

A separate effect of desertification, apart from any possible influence on rainfall, is an increase of soil erosion and dust storms (4), as shown in Fig 1 . This shows the close relationship between rainfall and dust.

Fig 1 . The frequency of dust storms at Gao (in the Sahel), compared with annual rainfall anomalies (from (1), after (4)). The anomaly unit is the regionally averaged departure from the long-term mean, divided by the standard deviation. The dust occurrence is expressed in terms of the number of days when there is dust haze.

  References

(1) Nicholson, S.E., C.J. Tucker and M.B. Ba 1998. Desertification, drought and surface vegetation: an example from the West African Sahel. Bull. Amer. Meteor. Soc., 79 , 815-29.

(2) Charney, J.G. 1975. Dynamics of deserts and drought in Sahel. Quart. J. Royal Meteor. Soc, 101 , 193-202.

(3) Xue, Y. and J. Shukla 1993. The influence of land surface properties on Sahel climate. J. Climate, 6 , 2232-45.

(4) N’Tchayi, M.G., J.J. Bertrand and S.E. Nicholson 1997. The diurnal and seasonal cycles of desert dust over Africa north of the equator. J. Appl. Meteor. 36 , 868-82.  

Desertification, land degradation and drought

Related sdgs, protect, restore and promote sustainable use ....

what is the desertion hypothesis

Description

Publications.

Paragraph 33 of the 2030 Agenda for Sustainable Development focuses on the linkage between sustainable management of the planet’s natural resources and social and economic development as well as on “strengthen cooperation on desertification, dust storms, land degradation and drought and promote resilience and disaster risk reduction” .

Sustainable Development Goal 15 of the 2030 Agenda aims to “protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss” .

The economic and social significance of a good land management, including soil and its contribution to economic growth and social progress is recognized in paragraph 205 of the Future We Want. In this context, Member States express their concern on the challenges posed to sustainable development by desertification, land degradation and drought, especially for Africa, LDCs and LLDCs. At the same time, Member States highlight the need to take action at national, regional and international level to reverse land degradation, catalyse financial resources, from both private and public donors and implement both the United Nations Convention to Combat Desertification (UNCCD) and its 10- Year Strategic Plan and Framework (2008-2018).

Furthermore, in paragraphs 207 and 208 of the Future We Want, Member States encourage and recognize the importance of partnerships and initiatives for the safeguarding of land resources, further development and implementation of scientifically based, sound and socially inclusive methods and indicators for monitoring and assessing the extent of desertification, land degradation and drought. The relevance of efforts underway to promote scientific research and strengthen the scientific base of activities to address desertification and drought under the UNCCD is also addressed.

Combating desertification and drought were discussed by the Commission on Sustainable Development in several sessions. In the framework of the Commission's multi-year work programme, CSD 16-17 focused, respectively in 2008 and 2009, on desertification and drought along with the interrelated issues of Land, Agriculture, Rural development and Africa.

In accordance with its multi-year programme of work, CSD-8 in 2000 reviewed integrated planning and management of land resources as its sectoral theme. In its decision 8/3 on integrated planning and management of land resources, the Commission on Sustainable Development noted the importance of addressing sustainable development through a holistic approach, such as ecosystem management, in order to meet the priority challenges of desertification and drought, sustainable mountain development, prevention and mitigation of land degradation, coastal zones, deforestation, climate change, rural and urban land use, urban growth and conservation of biological diversity.

The sectoral cluster of land, desertification, forests and biodiversity, as well as mountains (chapters 10-13 and 15 of Agenda 21) were considered by CSD-3 in 1995 and again at the five-year review in 1997.

The UN Conference on Environment and Development (UNCED) called upon the United Nations General Assembly to establish an Intergovernmental Negotiating Committee (INCD) to prepare, by June 1994, an international convention to combat desertification in those countries experiencing serious drought and/or desertification, particularly in Africa. The Convention was adopted in Paris on 17 June 1994 and opened for signature there on 14-15 October 1994. It entered into force on 26 December 1996.

Deserts are among the "fragile ecosystems" addressed by Agenda 21, and "combating desertification and drought" is the subject of Chapter 12. Desertification includes land degradation in arid, semi-arid and dry sub humid areas resulting from various factors, including climatic variations and human activities. Desertification affects as much as one-sixth of the world's population, seventy percent of all drylands, and one-quarter of the total land area of the world. It results in widespread poverty as well as in the degradation of billion hectares of rangeland and cropland.

Integrated planning and management of land resources is the subject of chapter 10 of Agenda 21, which deals with the cross-sectoral aspects of decision-making for the sustainable use and development of natural resources, including the soils, minerals, water and biota that land comprises. This broad integrative view of land resources, which are essential for life-support systems and the productive capacity of the environment, is the basis of Agenda 21's and the Commission on Sustainable Development's consideration of land issues.

Expanding human requirements and economic activities are placing ever increasing pressures on land resources, creating competition and conflicts and resulting in suboptimal use of resources. By examining all uses of land in an integrated manner, it makes it possible to minimize conflicts, to make the most efficient trade-offs and to link social and economic development with environmental protection and enhancement, thus helping to achieve the objectives of sustainable development. (Agenda 21, para 10.1) The Food and Agriculture Organization of the United Nations (FAO) is the task manager for chapter 10 of Agenda 21.

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  • January 2015 SDG 15 - Desertification SDG 15 aims at protecting, restoring and promoting sustainable use of terrestrial ecosystems, sustainable manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss. Target 15.3 in particular reads to achieve "by 2030, combat desertification, restore degraded land and soil, including land affected by desertification, drought and floods, and strive to achieve a land degradation-neutral world".
  • January 2012 Future We Want (Para 205-209) The economic and social significance of a good land management, including soil and its contribution to economic growth and social progress is also recognized in paragraph 205 of the Future We Want. In this context, Member States express their concern on the challenges posed to sustainable development by desertification, land degradation and drought, especially for Africa, LDCs and LLDCs. At the same time, Member States highlight the need to take action at national, regional and international level to reverse land degradation, catalyze financial resources, from both private and public donors and implement both the United Nations Convention to Combat Desertification (UNCCD) and its 10- Year Strategic Plan and Framework (2008-2018). Furthermore, in paragraphs 207 and 208 of the Future We Want, Member States encourage and recognize the importance of partnerships and initiatives for the safeguarding of land resources, further development and implementation of scientifically based, sound and socially inclusive methods and indicators for monitoring and assessing the extent of desertification, land degradation and drought. The relevance of efforts underway to promote scientific research and strengthen the scientific base of activities to address desertification and drought under the UNCCD is also taken into account by paragraph 208.
  • January 2010 UN Decade on Desertification Launched by the General Assembly with the adoption of Resolution A/RES/64/201, the UN Decade for Deserts and the Fight Against Desertification was designed to address the Parties'concern about the worsening of the situation of desertification and its negative impact on the achievement of the Millennium Development Goals. The Decade started in January 2010 and will end in December 2020 with the aim of promoting action ensuring the protection of dry-lands.
  • January 2008 CSD-16 (Chap.2 C,D,E) CSD-16 focused on the thematic cluster of agriculture, rural development, land, drought, desertification and Africa.
  • January 2006 Int. Year of Deserts and Desertification The International Year of Deserts and Desertification was launched to highlight the threat represented by the advancing of deserts and the loss it may cause to biodiversity. Through this International Year, the UN aimed at raising public awareness on this issue and at reversing the trend of desertification, setting the world on a safer and more sustainable path of development.
  • January 2000 CSD-8 (Chap. 4) As decided at UNGASS, the economic, sectoral and cross-sectoral themes under consideration for CSD-8 were sustainable agriculture and land management, integrating planning and management of land resources and financial resources, trade and investment and economic growth.CSD-6 to CSD-9 annually gathered at the UN Headquarters for spring meetings. Discussions at each session opened with multi-stakeholder dialogues, in which major groups were invited to make opening statements on selected themes followed by a dialogue with government representatives.
  • January 1996 UNCCD The only legally binding international agreement connecting environment and development to sustainable land management, UNCCD addresses the arid, semi-arid and dry sub-humid areas, known as the drylands, where some of the most vulnerable ecosystems and peoples can be found. In 2007 the 10-Year Strategy of the UNCCD (2008-2018) was adopted and on that occasion, parties to the Convention further specified their goals: "to forge a global partnership to reverse and prevent desertification/land degradation and to mitigate the effects of drought in affected areas in order to support poverty reduction and environmental sustainability". The Convention was adopted in Paris on 17 June 1994 and entered into force on 26 December 1996, 90 days after the 50th ratification was received. 194 countries and the European Union are Parties as at April 2015.
  • January 1992 Agenda 21 (Chap. 10 and 12) Integrated planning and management of land resources is the subject of chapter 10 of Agenda 21, which deals with the cross-sectoral aspects of decision-making for the sustainable use and development of natural resources, including the soils, minerals and water that land comprises. Included in the sections devoted to the management of fragile ecosystems, chapter 12 has focused on combating desertification and droughts. The priority to keep in mind while combating desertification is identified by Chap 12.3 in the need to implement "preventive measures for lands that are not yet degraded, or which are only slightly degraded. However, the severely degraded areas should not be neglected. In combating desertification and drought, the participation of local communities, rural organizations, national Governments, non-governmental organizations and international and regional organizations is essential".
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Desertification in the Karoo

Driving eastward out of the Cape, through the winelands around Paarl and away from the region of winter rainfall the landscape becomes arid. Sheep grazing replaces the vineyards except in irrigated areas where fruits can still be grown.

This is a hostile landscape to which early European colonisers originally brought cattle, but moved-on in search of better pastures. The settlers learned to live with the periodic droughts and unfamiliar wild animals, building homesteads near sources of water, replacing cattle with hardier sheep, and establishing towns like Graaf Reinet in the 1820s.

Sheep-ranges were fenced and protected and jackal predators eradicated. As the control of nature increased, so did populations of sheep.

The great semi-arid area stretching eastwards from the Cape is called the Karoo. Typically, it is flat dry shrubland with grass-growth restricted to the moistness of the occasional mountain ranges. Rainfall is sporadic, less than 500 mm a year, in some places a great deal less. Periods of drought last for several years, affecting the region and its plant growth. Notable droughts occurred in the periods 1919-31, 1944-49 and 1962-73. Since 1974 has been a relatively wet period.

Karoo lamb is succulent herby meat, much appreciated on the braais, or barbecues, of South Africa, but the vast region of the Karoo produces little else of note. In a time of farm incomes that are falling, there is much talk of developing game parks and attracting overseas tourists to provide a living.

White farmers making a precarious living from sheep in the Karoo. They feel marginalised in a country with politically different and largely urban priorities.

Of great concern to the farmers is the suggestion that the landscape is becoming more hostile to farming, and eventually unsuitable for livestock.

First suggested by a French-forester named Aubréville in the late nineteenth century, and forcibly advocated in South Africa by J.P.H.Acocks in the 1950s, the term 'desertification' implies the advance of desert-like conditions - a growing aridification. Acocks described a desert margin advancing northeastwards towards Pretoria - a powerful image since this is the seat of South African government.

In the days when public values were Boer farming values, desertification was seen as a threat to rural livelihoods and a cause for concern. Government spent large sums of money subsidising farming systems that arguably, as in other parts of the world, were unsustainable.

Sheep prices were high, and grants were available for fencing, water conservation and anti-erosion measures such as dams. These subsidies and measures further enabled farmers to overstock with sheep.

Nowadays, there is an additional cause for concern. Desertification implies soil erosion. Soils are washed into streams and eventually silt-up reservoirs. South Africa has a water resource problem – and loss of water storage in reservoirs contributes to the scarcity.

The concept of desertification has been the subject of fierce debate. The vegetation of the Karoo has changed from a mix of livestock-edible grasses and shrubs, to undesirable shrubs which are less palatable to sheep.

One of the problems with the loss of grasses is that a patchy shrub-dominated landscape has much bare ground, causing increased potential for rainfall runoff and soil erosion. Controversy rages around why these changes have occurred. Is it climate-induced, detrimental human impact, climate and human impact, or just a natural process in marginal-arid areas of the world?

Semi-arid areas are notoriously sensitive to climate variability and the Karoo has had many droughts, but much of the Karoo has also had very high numbers of sheep, until fairly recently. Overgrazing is recognised worldwide as an impact on vegetation that leads to the land degradation that is soil erosion. Together with occasional droughts, the Karoo’s dense sheep populations could explain the cause of desertification in the region.

If drought alone were the cause of the vegetation change, then relating change to cycles of drought would test the hypothesis. Recent research confirms that the vegetation type has changed, but it does not provide reliable dates for the changes.

The landscape of the Karoo shows evidence of desertification in that systems of deep gullies and crazy-paved badlands scar much of the landscape. These are likely to have formed when vegetation decline produced bare ground through loss of grasses that enables soil erosion by rainfall and runoff.

Dating the gullies and badlands is crucial to explaining the causes of desertification in the Karoo.

In the Sneeuberg uplands, gully systems developed when the first Europeans moved through the area in the early nineteenth century. At that time, cattle drank in streams that now lie at the bottom of six metre deep gullies, and hippopotami wallowed in pools that no longer exist. The gullies have continued to deepen to the extent that small dams built in the 1950s quickly filled with sediment.

Fences built on flatlands in the 1930s now cross deep gullies. Similarly, the badlands seem rather recent in age. During present-day storms, considerable erosion occurs. Once formed the badlands appear very difficult to revegetate, even with greatly reduced sheep numbers.

The desertified areas of the Karoo, gullied and lacking vegetation or growing unpalatable shrubs, seem likely to be a product of dense sheep populations in the 100 years from 1860 to 1960.

If this is the case, the desertification of the Karoo is an indictment of the introduction and development of European farming systems in fragile semi-arid landscapes that are subject to drought. Similar stories are told in the arid farming regions of western USA, Australia and New Zealand, and the controversy over the causes remain.

  • Desertification
  • Climate crisis

Most viewed

What is a scientific hypothesis?

It's the initial building block in the scientific method.

A girl looks at plants in a test tube for a science experiment. What's her scientific hypothesis?

Hypothesis basics

What makes a hypothesis testable.

  • Types of hypotheses
  • Hypothesis versus theory

Additional resources

Bibliography.

A scientific hypothesis is a tentative, testable explanation for a phenomenon in the natural world. It's the initial building block in the scientific method . Many describe it as an "educated guess" based on prior knowledge and observation. While this is true, a hypothesis is more informed than a guess. While an "educated guess" suggests a random prediction based on a person's expertise, developing a hypothesis requires active observation and background research. 

The basic idea of a hypothesis is that there is no predetermined outcome. For a solution to be termed a scientific hypothesis, it has to be an idea that can be supported or refuted through carefully crafted experimentation or observation. This concept, called falsifiability and testability, was advanced in the mid-20th century by Austrian-British philosopher Karl Popper in his famous book "The Logic of Scientific Discovery" (Routledge, 1959).

A key function of a hypothesis is to derive predictions about the results of future experiments and then perform those experiments to see whether they support the predictions.

A hypothesis is usually written in the form of an if-then statement, which gives a possibility (if) and explains what may happen because of the possibility (then). The statement could also include "may," according to California State University, Bakersfield .

Here are some examples of hypothesis statements:

  • If garlic repels fleas, then a dog that is given garlic every day will not get fleas.
  • If sugar causes cavities, then people who eat a lot of candy may be more prone to cavities.
  • If ultraviolet light can damage the eyes, then maybe this light can cause blindness.

A useful hypothesis should be testable and falsifiable. That means that it should be possible to prove it wrong. A theory that can't be proved wrong is nonscientific, according to Karl Popper's 1963 book " Conjectures and Refutations ."

An example of an untestable statement is, "Dogs are better than cats." That's because the definition of "better" is vague and subjective. However, an untestable statement can be reworded to make it testable. For example, the previous statement could be changed to this: "Owning a dog is associated with higher levels of physical fitness than owning a cat." With this statement, the researcher can take measures of physical fitness from dog and cat owners and compare the two.

Types of scientific hypotheses

In an experiment, researchers generally state their hypotheses in two ways. The null hypothesis predicts that there will be no relationship between the variables tested, or no difference between the experimental groups. The alternative hypothesis predicts the opposite: that there will be a difference between the experimental groups. This is usually the hypothesis scientists are most interested in, according to the University of Miami .

For example, a null hypothesis might state, "There will be no difference in the rate of muscle growth between people who take a protein supplement and people who don't." The alternative hypothesis would state, "There will be a difference in the rate of muscle growth between people who take a protein supplement and people who don't."

If the results of the experiment show a relationship between the variables, then the null hypothesis has been rejected in favor of the alternative hypothesis, according to the book " Research Methods in Psychology " (​​BCcampus, 2015). 

There are other ways to describe an alternative hypothesis. The alternative hypothesis above does not specify a direction of the effect, only that there will be a difference between the two groups. That type of prediction is called a two-tailed hypothesis. If a hypothesis specifies a certain direction — for example, that people who take a protein supplement will gain more muscle than people who don't — it is called a one-tailed hypothesis, according to William M. K. Trochim , a professor of Policy Analysis and Management at Cornell University.

Sometimes, errors take place during an experiment. These errors can happen in one of two ways. A type I error is when the null hypothesis is rejected when it is true. This is also known as a false positive. A type II error occurs when the null hypothesis is not rejected when it is false. This is also known as a false negative, according to the University of California, Berkeley . 

A hypothesis can be rejected or modified, but it can never be proved correct 100% of the time. For example, a scientist can form a hypothesis stating that if a certain type of tomato has a gene for red pigment, that type of tomato will be red. During research, the scientist then finds that each tomato of this type is red. Though the findings confirm the hypothesis, there may be a tomato of that type somewhere in the world that isn't red. Thus, the hypothesis is true, but it may not be true 100% of the time.

Scientific theory vs. scientific hypothesis

The best hypotheses are simple. They deal with a relatively narrow set of phenomena. But theories are broader; they generally combine multiple hypotheses into a general explanation for a wide range of phenomena, according to the University of California, Berkeley . For example, a hypothesis might state, "If animals adapt to suit their environments, then birds that live on islands with lots of seeds to eat will have differently shaped beaks than birds that live on islands with lots of insects to eat." After testing many hypotheses like these, Charles Darwin formulated an overarching theory: the theory of evolution by natural selection.

"Theories are the ways that we make sense of what we observe in the natural world," Tanner said. "Theories are structures of ideas that explain and interpret facts." 

  • Read more about writing a hypothesis, from the American Medical Writers Association.
  • Find out why a hypothesis isn't always necessary in science, from The American Biology Teacher.
  • Learn about null and alternative hypotheses, from Prof. Essa on YouTube .

Encyclopedia Britannica. Scientific Hypothesis. Jan. 13, 2022. https://www.britannica.com/science/scientific-hypothesis

Karl Popper, "The Logic of Scientific Discovery," Routledge, 1959.

California State University, Bakersfield, "Formatting a testable hypothesis." https://www.csub.edu/~ddodenhoff/Bio100/Bio100sp04/formattingahypothesis.htm  

Karl Popper, "Conjectures and Refutations," Routledge, 1963.

Price, P., Jhangiani, R., & Chiang, I., "Research Methods of Psychology — 2nd Canadian Edition," BCcampus, 2015.‌

University of Miami, "The Scientific Method" http://www.bio.miami.edu/dana/161/evolution/161app1_scimethod.pdf  

William M.K. Trochim, "Research Methods Knowledge Base," https://conjointly.com/kb/hypotheses-explained/  

University of California, Berkeley, "Multiple Hypothesis Testing and False Discovery Rate" https://www.stat.berkeley.edu/~hhuang/STAT141/Lecture-FDR.pdf  

University of California, Berkeley, "Science at multiple levels" https://undsci.berkeley.edu/article/0_0_0/howscienceworks_19

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  • Scientific Methods

What is Hypothesis?

We have heard of many hypotheses which have led to great inventions in science. Assumptions that are made on the basis of some evidence are known as hypotheses. In this article, let us learn in detail about the hypothesis and the type of hypothesis with examples.

A hypothesis is an assumption that is made based on some evidence. This is the initial point of any investigation that translates the research questions into predictions. It includes components like variables, population and the relation between the variables. A research hypothesis is a hypothesis that is used to test the relationship between two or more variables.

Characteristics of Hypothesis

Following are the characteristics of the hypothesis:

  • The hypothesis should be clear and precise to consider it to be reliable.
  • If the hypothesis is a relational hypothesis, then it should be stating the relationship between variables.
  • The hypothesis must be specific and should have scope for conducting more tests.
  • The way of explanation of the hypothesis must be very simple and it should also be understood that the simplicity of the hypothesis is not related to its significance.

Sources of Hypothesis

Following are the sources of hypothesis:

  • The resemblance between the phenomenon.
  • Observations from past studies, present-day experiences and from the competitors.
  • Scientific theories.
  • General patterns that influence the thinking process of people.

Types of Hypothesis

There are six forms of hypothesis and they are:

  • Simple hypothesis
  • Complex hypothesis
  • Directional hypothesis
  • Non-directional hypothesis
  • Null hypothesis
  • Associative and casual hypothesis

Simple Hypothesis

It shows a relationship between one dependent variable and a single independent variable. For example – If you eat more vegetables, you will lose weight faster. Here, eating more vegetables is an independent variable, while losing weight is the dependent variable.

Complex Hypothesis

It shows the relationship between two or more dependent variables and two or more independent variables. Eating more vegetables and fruits leads to weight loss, glowing skin, and reduces the risk of many diseases such as heart disease.

Directional Hypothesis

It shows how a researcher is intellectual and committed to a particular outcome. The relationship between the variables can also predict its nature. For example- children aged four years eating proper food over a five-year period are having higher IQ levels than children not having a proper meal. This shows the effect and direction of the effect.

Non-directional Hypothesis

It is used when there is no theory involved. It is a statement that a relationship exists between two variables, without predicting the exact nature (direction) of the relationship.

Null Hypothesis

It provides a statement which is contrary to the hypothesis. It’s a negative statement, and there is no relationship between independent and dependent variables. The symbol is denoted by “H O ”.

Associative and Causal Hypothesis

Associative hypothesis occurs when there is a change in one variable resulting in a change in the other variable. Whereas, the causal hypothesis proposes a cause and effect interaction between two or more variables.

Examples of Hypothesis

Following are the examples of hypotheses based on their types:

  • Consumption of sugary drinks every day leads to obesity is an example of a simple hypothesis.
  • All lilies have the same number of petals is an example of a null hypothesis.
  • If a person gets 7 hours of sleep, then he will feel less fatigue than if he sleeps less. It is an example of a directional hypothesis.

Functions of Hypothesis

Following are the functions performed by the hypothesis:

  • Hypothesis helps in making an observation and experiments possible.
  • It becomes the start point for the investigation.
  • Hypothesis helps in verifying the observations.
  • It helps in directing the inquiries in the right direction.

How will Hypothesis help in the Scientific Method?

Researchers use hypotheses to put down their thoughts directing how the experiment would take place. Following are the steps that are involved in the scientific method:

  • Formation of question
  • Doing background research
  • Creation of hypothesis
  • Designing an experiment
  • Collection of data
  • Result analysis
  • Summarizing the experiment
  • Communicating the results

Frequently Asked Questions – FAQs

What is hypothesis.

A hypothesis is an assumption made based on some evidence.

Give an example of simple hypothesis?

What are the types of hypothesis.

Types of hypothesis are:

  • Associative and Casual hypothesis

State true or false: Hypothesis is the initial point of any investigation that translates the research questions into a prediction.

Define complex hypothesis..

A complex hypothesis shows the relationship between two or more dependent variables and two or more independent variables.

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Research Hypothesis In Psychology: Types, & Examples

Saul Mcleod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul Mcleod, Ph.D., is a qualified psychology teacher with over 18 years experience of working in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

Learn about our Editorial Process

Olivia Guy-Evans, MSc

Associate Editor for Simply Psychology

BSc (Hons) Psychology, MSc Psychology of Education

Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

On This Page:

A research hypothesis, in its plural form “hypotheses,” is a specific, testable prediction about the anticipated results of a study, established at its outset. It is a key component of the scientific method .

Hypotheses connect theory to data and guide the research process towards expanding scientific understanding

Some key points about hypotheses:

  • A hypothesis expresses an expected pattern or relationship. It connects the variables under investigation.
  • It is stated in clear, precise terms before any data collection or analysis occurs. This makes the hypothesis testable.
  • A hypothesis must be falsifiable. It should be possible, even if unlikely in practice, to collect data that disconfirms rather than supports the hypothesis.
  • Hypotheses guide research. Scientists design studies to explicitly evaluate hypotheses about how nature works.
  • For a hypothesis to be valid, it must be testable against empirical evidence. The evidence can then confirm or disprove the testable predictions.
  • Hypotheses are informed by background knowledge and observation, but go beyond what is already known to propose an explanation of how or why something occurs.
Predictions typically arise from a thorough knowledge of the research literature, curiosity about real-world problems or implications, and integrating this to advance theory. They build on existing literature while providing new insight.

Types of Research Hypotheses

Alternative hypothesis.

The research hypothesis is often called the alternative or experimental hypothesis in experimental research.

It typically suggests a potential relationship between two key variables: the independent variable, which the researcher manipulates, and the dependent variable, which is measured based on those changes.

The alternative hypothesis states a relationship exists between the two variables being studied (one variable affects the other).

A hypothesis is a testable statement or prediction about the relationship between two or more variables. It is a key component of the scientific method. Some key points about hypotheses:

  • Important hypotheses lead to predictions that can be tested empirically. The evidence can then confirm or disprove the testable predictions.

In summary, a hypothesis is a precise, testable statement of what researchers expect to happen in a study and why. Hypotheses connect theory to data and guide the research process towards expanding scientific understanding.

An experimental hypothesis predicts what change(s) will occur in the dependent variable when the independent variable is manipulated.

It states that the results are not due to chance and are significant in supporting the theory being investigated.

The alternative hypothesis can be directional, indicating a specific direction of the effect, or non-directional, suggesting a difference without specifying its nature. It’s what researchers aim to support or demonstrate through their study.

Null Hypothesis

The null hypothesis states no relationship exists between the two variables being studied (one variable does not affect the other). There will be no changes in the dependent variable due to manipulating the independent variable.

It states results are due to chance and are not significant in supporting the idea being investigated.

The null hypothesis, positing no effect or relationship, is a foundational contrast to the research hypothesis in scientific inquiry. It establishes a baseline for statistical testing, promoting objectivity by initiating research from a neutral stance.

Many statistical methods are tailored to test the null hypothesis, determining the likelihood of observed results if no true effect exists.

This dual-hypothesis approach provides clarity, ensuring that research intentions are explicit, and fosters consistency across scientific studies, enhancing the standardization and interpretability of research outcomes.

Nondirectional Hypothesis

A non-directional hypothesis, also known as a two-tailed hypothesis, predicts that there is a difference or relationship between two variables but does not specify the direction of this relationship.

It merely indicates that a change or effect will occur without predicting which group will have higher or lower values.

For example, “There is a difference in performance between Group A and Group B” is a non-directional hypothesis.

Directional Hypothesis

A directional (one-tailed) hypothesis predicts the nature of the effect of the independent variable on the dependent variable. It predicts in which direction the change will take place. (i.e., greater, smaller, less, more)

It specifies whether one variable is greater, lesser, or different from another, rather than just indicating that there’s a difference without specifying its nature.

For example, “Exercise increases weight loss” is a directional hypothesis.

hypothesis

Falsifiability

The Falsification Principle, proposed by Karl Popper , is a way of demarcating science from non-science. It suggests that for a theory or hypothesis to be considered scientific, it must be testable and irrefutable.

Falsifiability emphasizes that scientific claims shouldn’t just be confirmable but should also have the potential to be proven wrong.

It means that there should exist some potential evidence or experiment that could prove the proposition false.

However many confirming instances exist for a theory, it only takes one counter observation to falsify it. For example, the hypothesis that “all swans are white,” can be falsified by observing a black swan.

For Popper, science should attempt to disprove a theory rather than attempt to continually provide evidence to support a research hypothesis.

Can a Hypothesis be Proven?

Hypotheses make probabilistic predictions. They state the expected outcome if a particular relationship exists. However, a study result supporting a hypothesis does not definitively prove it is true.

All studies have limitations. There may be unknown confounding factors or issues that limit the certainty of conclusions. Additional studies may yield different results.

In science, hypotheses can realistically only be supported with some degree of confidence, not proven. The process of science is to incrementally accumulate evidence for and against hypothesized relationships in an ongoing pursuit of better models and explanations that best fit the empirical data. But hypotheses remain open to revision and rejection if that is where the evidence leads.
  • Disproving a hypothesis is definitive. Solid disconfirmatory evidence will falsify a hypothesis and require altering or discarding it based on the evidence.
  • However, confirming evidence is always open to revision. Other explanations may account for the same results, and additional or contradictory evidence may emerge over time.

We can never 100% prove the alternative hypothesis. Instead, we see if we can disprove, or reject the null hypothesis.

If we reject the null hypothesis, this doesn’t mean that our alternative hypothesis is correct but does support the alternative/experimental hypothesis.

Upon analysis of the results, an alternative hypothesis can be rejected or supported, but it can never be proven to be correct. We must avoid any reference to results proving a theory as this implies 100% certainty, and there is always a chance that evidence may exist which could refute a theory.

How to Write a Hypothesis

  • Identify variables . The researcher manipulates the independent variable and the dependent variable is the measured outcome.
  • Operationalized the variables being investigated . Operationalization of a hypothesis refers to the process of making the variables physically measurable or testable, e.g. if you are about to study aggression, you might count the number of punches given by participants.
  • Decide on a direction for your prediction . If there is evidence in the literature to support a specific effect of the independent variable on the dependent variable, write a directional (one-tailed) hypothesis. If there are limited or ambiguous findings in the literature regarding the effect of the independent variable on the dependent variable, write a non-directional (two-tailed) hypothesis.
  • Make it Testable : Ensure your hypothesis can be tested through experimentation or observation. It should be possible to prove it false (principle of falsifiability).
  • Clear & concise language . A strong hypothesis is concise (typically one to two sentences long), and formulated using clear and straightforward language, ensuring it’s easily understood and testable.

Consider a hypothesis many teachers might subscribe to: students work better on Monday morning than on Friday afternoon (IV=Day, DV= Standard of work).

Now, if we decide to study this by giving the same group of students a lesson on a Monday morning and a Friday afternoon and then measuring their immediate recall of the material covered in each session, we would end up with the following:

  • The alternative hypothesis states that students will recall significantly more information on a Monday morning than on a Friday afternoon.
  • The null hypothesis states that there will be no significant difference in the amount recalled on a Monday morning compared to a Friday afternoon. Any difference will be due to chance or confounding factors.

More Examples

  • Memory : Participants exposed to classical music during study sessions will recall more items from a list than those who studied in silence.
  • Social Psychology : Individuals who frequently engage in social media use will report higher levels of perceived social isolation compared to those who use it infrequently.
  • Developmental Psychology : Children who engage in regular imaginative play have better problem-solving skills than those who don’t.
  • Clinical Psychology : Cognitive-behavioral therapy will be more effective in reducing symptoms of anxiety over a 6-month period compared to traditional talk therapy.
  • Cognitive Psychology : Individuals who multitask between various electronic devices will have shorter attention spans on focused tasks than those who single-task.
  • Health Psychology : Patients who practice mindfulness meditation will experience lower levels of chronic pain compared to those who don’t meditate.
  • Organizational Psychology : Employees in open-plan offices will report higher levels of stress than those in private offices.
  • Behavioral Psychology : Rats rewarded with food after pressing a lever will press it more frequently than rats who receive no reward.

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Definition of desertion

  • abandonment
  • dereliction

Examples of desertion in a Sentence

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'desertion.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

borrowed from Middle French & Latin; Middle French, borrowed from Latin dēsertiōn-, dēsertiō, from dēserere "to part company with, abandon, leave uninhabited, leave in the lurch" + -tiōn-, -tiō, suffix of verbal action — more at desert entry 3

1591, in the meaning defined at sense 1

Dictionary Entries Near desertion

desertification

desert ironwood

Cite this Entry

“Desertion.” Merriam-Webster.com Dictionary , Merriam-Webster, https://www.merriam-webster.com/dictionary/desertion. Accessed 19 Mar. 2024.

Legal Definition

Legal definition of desertion.

Note: Desertion is a ground for divorce in many states.

More from Merriam-Webster on desertion

Nglish: Translation of desertion for Spanish Speakers

Britannica English: Translation of desertion for Arabic Speakers

Britannica.com: Encyclopedia article about desertion

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Methodology

  • How to Write a Strong Hypothesis | Steps & Examples

How to Write a Strong Hypothesis | Steps & Examples

Published on May 6, 2022 by Shona McCombes . Revised on November 20, 2023.

A hypothesis is a statement that can be tested by scientific research. If you want to test a relationship between two or more variables, you need to write hypotheses before you start your experiment or data collection .

Example: Hypothesis

Daily apple consumption leads to fewer doctor’s visits.

Table of contents

What is a hypothesis, developing a hypothesis (with example), hypothesis examples, other interesting articles, frequently asked questions about writing hypotheses.

A hypothesis states your predictions about what your research will find. It is a tentative answer to your research question that has not yet been tested. For some research projects, you might have to write several hypotheses that address different aspects of your research question.

A hypothesis is not just a guess – it should be based on existing theories and knowledge. It also has to be testable, which means you can support or refute it through scientific research methods (such as experiments, observations and statistical analysis of data).

Variables in hypotheses

Hypotheses propose a relationship between two or more types of variables .

  • An independent variable is something the researcher changes or controls.
  • A dependent variable is something the researcher observes and measures.

If there are any control variables , extraneous variables , or confounding variables , be sure to jot those down as you go to minimize the chances that research bias  will affect your results.

In this example, the independent variable is exposure to the sun – the assumed cause . The dependent variable is the level of happiness – the assumed effect .

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Step 1. Ask a question

Writing a hypothesis begins with a research question that you want to answer. The question should be focused, specific, and researchable within the constraints of your project.

Step 2. Do some preliminary research

Your initial answer to the question should be based on what is already known about the topic. Look for theories and previous studies to help you form educated assumptions about what your research will find.

At this stage, you might construct a conceptual framework to ensure that you’re embarking on a relevant topic . This can also help you identify which variables you will study and what you think the relationships are between them. Sometimes, you’ll have to operationalize more complex constructs.

Step 3. Formulate your hypothesis

Now you should have some idea of what you expect to find. Write your initial answer to the question in a clear, concise sentence.

4. Refine your hypothesis

You need to make sure your hypothesis is specific and testable. There are various ways of phrasing a hypothesis, but all the terms you use should have clear definitions, and the hypothesis should contain:

  • The relevant variables
  • The specific group being studied
  • The predicted outcome of the experiment or analysis

5. Phrase your hypothesis in three ways

To identify the variables, you can write a simple prediction in  if…then form. The first part of the sentence states the independent variable and the second part states the dependent variable.

In academic research, hypotheses are more commonly phrased in terms of correlations or effects, where you directly state the predicted relationship between variables.

If you are comparing two groups, the hypothesis can state what difference you expect to find between them.

6. Write a null hypothesis

If your research involves statistical hypothesis testing , you will also have to write a null hypothesis . The null hypothesis is the default position that there is no association between the variables. The null hypothesis is written as H 0 , while the alternative hypothesis is H 1 or H a .

  • H 0 : The number of lectures attended by first-year students has no effect on their final exam scores.
  • H 1 : The number of lectures attended by first-year students has a positive effect on their final exam scores.

If you want to know more about the research process , methodology , research bias , or statistics , make sure to check out some of our other articles with explanations and examples.

  • Sampling methods
  • Simple random sampling
  • Stratified sampling
  • Cluster sampling
  • Likert scales
  • Reproducibility

 Statistics

  • Null hypothesis
  • Statistical power
  • Probability distribution
  • Effect size
  • Poisson distribution

Research bias

  • Optimism bias
  • Cognitive bias
  • Implicit bias
  • Hawthorne effect
  • Anchoring bias
  • Explicit bias

A hypothesis is not just a guess — it should be based on existing theories and knowledge. It also has to be testable, which means you can support or refute it through scientific research methods (such as experiments, observations and statistical analysis of data).

Null and alternative hypotheses are used in statistical hypothesis testing . The null hypothesis of a test always predicts no effect or no relationship between variables, while the alternative hypothesis states your research prediction of an effect or relationship.

Hypothesis testing is a formal procedure for investigating our ideas about the world using statistics. It is used by scientists to test specific predictions, called hypotheses , by calculating how likely it is that a pattern or relationship between variables could have arisen by chance.

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What Is a Hypothesis? (Science)

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A hypothesis (plural hypotheses) is a proposed explanation for an observation. The definition depends on the subject.

In science, a hypothesis is part of the scientific method. It is a prediction or explanation that is tested by an experiment. Observations and experiments may disprove a scientific hypothesis, but can never entirely prove one.

In the study of logic, a hypothesis is an if-then proposition, typically written in the form, "If X , then Y ."

In common usage, a hypothesis is simply a proposed explanation or prediction, which may or may not be tested.

Writing a Hypothesis

Most scientific hypotheses are proposed in the if-then format because it's easy to design an experiment to see whether or not a cause and effect relationship exists between the independent variable and the dependent variable . The hypothesis is written as a prediction of the outcome of the experiment.

  • Null Hypothesis and Alternative Hypothesis

Statistically, it's easier to show there is no relationship between two variables than to support their connection. So, scientists often propose the null hypothesis . The null hypothesis assumes changing the independent variable will have no effect on the dependent variable.

In contrast, the alternative hypothesis suggests changing the independent variable will have an effect on the dependent variable. Designing an experiment to test this hypothesis can be trickier because there are many ways to state an alternative hypothesis.

For example, consider a possible relationship between getting a good night's sleep and getting good grades. The null hypothesis might be stated: "The number of hours of sleep students get is unrelated to their grades" or "There is no correlation between hours of sleep and grades."

An experiment to test this hypothesis might involve collecting data, recording average hours of sleep for each student and grades. If a student who gets eight hours of sleep generally does better than students who get four hours of sleep or 10 hours of sleep, the hypothesis might be rejected.

But the alternative hypothesis is harder to propose and test. The most general statement would be: "The amount of sleep students get affects their grades." The hypothesis might also be stated as "If you get more sleep, your grades will improve" or "Students who get nine hours of sleep have better grades than those who get more or less sleep."

In an experiment, you can collect the same data, but the statistical analysis is less likely to give you a high confidence limit.

Usually, a scientist starts out with the null hypothesis. From there, it may be possible to propose and test an alternative hypothesis, to narrow down the relationship between the variables.

Example of a Hypothesis

Examples of a hypothesis include:

  • If you drop a rock and a feather, (then) they will fall at the same rate.
  • Plants need sunlight in order to live. (if sunlight, then life)
  • Eating sugar gives you energy. (if sugar, then energy)
  • White, Jay D.  Research in Public Administration . Conn., 1998.
  • Schick, Theodore, and Lewis Vaughn.  How to Think about Weird Things: Critical Thinking for a New Age . McGraw-Hill Higher Education, 2002.
  • Null Hypothesis Definition and Examples
  • Definition of a Hypothesis
  • What Are the Elements of a Good Hypothesis?
  • Six Steps of the Scientific Method
  • What Are Examples of a Hypothesis?
  • Understanding Simple vs Controlled Experiments
  • Scientific Method Flow Chart
  • Scientific Method Vocabulary Terms
  • What Is a Testable Hypothesis?
  • Null Hypothesis Examples
  • What 'Fail to Reject' Means in a Hypothesis Test
  • How To Design a Science Fair Experiment
  • What Is an Experiment? Definition and Design
  • Hypothesis Test for the Difference of Two Population Proportions
  • How to Conduct a Hypothesis Test

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Think about something strange and unexplainable in your life. Maybe you get a headache right before it rains, or maybe you think your favorite sports team wins when you wear a certain color. If you wanted to see whether these are just coincidences or scientific fact, you would form a hypothesis, then create an experiment to see whether that hypothesis is true or not. 

But what is a hypothesis, anyway? If you’re not sure about what a hypothesis is--or how to test for one!--you’re in the right place. This article will teach you everything you need to know about hypotheses, including: 

  • Defining the term “hypothesis” 
  • Providing hypothesis examples 
  • Giving you tips for how to write your own hypothesis 

So let’s get started!

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What Is a Hypothesis?

Merriam Webster defines a hypothesis as “an assumption or concession made for the sake of argument.” In other words, a hypothesis is an educated guess . Scientists make a reasonable assumption--or a hypothesis--then design an experiment to test whether it’s true or not. Keep in mind that in science, a hypothesis should be testable. You have to be able to design an experiment that tests your hypothesis in order for it to be valid. 

As you could assume from that statement, it’s easy to make a bad hypothesis. But when you’re holding an experiment, it’s even more important that your guesses be good...after all, you’re spending time (and maybe money!) to figure out more about your observation. That’s why we refer to a hypothesis as an educated guess--good hypotheses are based on existing data and research to make them as sound as possible.

Hypotheses are one part of what’s called the scientific method .  Every (good) experiment or study is based in the scientific method. The scientific method gives order and structure to experiments and ensures that interference from scientists or outside influences does not skew the results. It’s important that you understand the concepts of the scientific method before holding your own experiment. Though it may vary among scientists, the scientific method is generally made up of six steps (in order):

  • Observation
  • Asking questions
  • Forming a hypothesis
  • Analyze the data
  • Communicate your results

You’ll notice that the hypothesis comes pretty early on when conducting an experiment. That’s because experiments work best when they’re trying to answer one specific question. And you can’t conduct an experiment until you know what you’re trying to prove!

Independent and Dependent Variables 

After doing your research, you’re ready for another important step in forming your hypothesis: identifying variables. Variables are basically any factor that could influence the outcome of your experiment . Variables have to be measurable and related to the topic being studied.

There are two types of variables:  independent variables and dependent variables. I ndependent variables remain constant . For example, age is an independent variable; it will stay the same, and researchers can look at different ages to see if it has an effect on the dependent variable. 

Speaking of dependent variables... dependent variables are subject to the influence of the independent variable , meaning that they are not constant. Let’s say you want to test whether a person’s age affects how much sleep they need. In that case, the independent variable is age (like we mentioned above), and the dependent variable is how much sleep a person gets. 

Variables will be crucial in writing your hypothesis. You need to be able to identify which variable is which, as both the independent and dependent variables will be written into your hypothesis. For instance, in a study about exercise, the independent variable might be the speed at which the respondents walk for thirty minutes, and the dependent variable would be their heart rate. In your study and in your hypothesis, you’re trying to understand the relationship between the two variables.

Elements of a Good Hypothesis

The best hypotheses start by asking the right questions . For instance, if you’ve observed that the grass is greener when it rains twice a week, you could ask what kind of grass it is, what elevation it’s at, and if the grass across the street responds to rain in the same way. Any of these questions could become the backbone of experiments to test why the grass gets greener when it rains fairly frequently.

As you’re asking more questions about your first observation, make sure you’re also making more observations . If it doesn’t rain for two weeks and the grass still looks green, that’s an important observation that could influence your hypothesis. You'll continue observing all throughout your experiment, but until the hypothesis is finalized, every observation should be noted.

Finally, you should consult secondary research before writing your hypothesis . Secondary research is comprised of results found and published by other people. You can usually find this information online or at your library. Additionally, m ake sure the research you find is credible and related to your topic. If you’re studying the correlation between rain and grass growth, it would help you to research rain patterns over the past twenty years for your county, published by a local agricultural association. You should also research the types of grass common in your area, the type of grass in your lawn, and whether anyone else has conducted experiments about your hypothesis. Also be sure you’re checking the quality of your research . Research done by a middle school student about what minerals can be found in rainwater would be less useful than an article published by a local university.

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Writing Your Hypothesis

Once you’ve considered all of the factors above, you’re ready to start writing your hypothesis. Hypotheses usually take a certain form when they’re written out in a research report.

When you boil down your hypothesis statement, you are writing down your best guess and not the question at hand . This means that your statement should be written as if it is fact already, even though you are simply testing it.

The reason for this is that, after you have completed your study, you'll either accept or reject your if-then or your null hypothesis. All hypothesis testing examples should be measurable and able to be confirmed or denied. You cannot confirm a question, only a statement! 

In fact, you come up with hypothesis examples all the time! For instance, when you guess on the outcome of a basketball game, you don’t say, “Will the Miami Heat beat the Boston Celtics?” but instead, “I think the Miami Heat will beat the Boston Celtics.” You state it as if it is already true, even if it turns out you’re wrong. You do the same thing when writing your hypothesis.

Additionally, keep in mind that hypotheses can range from very specific to very broad.  These hypotheses can be specific, but if your hypothesis testing examples involve a broad range of causes and effects, your hypothesis can also be broad.  

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The Two Types of Hypotheses

Now that you understand what goes into a hypothesis, it’s time to look more closely at the two most common types of hypothesis: the if-then hypothesis and the null hypothesis.

#1: If-Then Hypotheses

First of all, if-then hypotheses typically follow this formula:

If ____ happens, then ____ will happen.

The goal of this type of hypothesis is to test the causal relationship between the independent and dependent variable. It’s fairly simple, and each hypothesis can vary in how detailed it can be. We create if-then hypotheses all the time with our daily predictions. Here are some examples of hypotheses that use an if-then structure from daily life: 

  • If I get enough sleep, I’ll be able to get more work done tomorrow.
  • If the bus is on time, I can make it to my friend’s birthday party. 
  • If I study every night this week, I’ll get a better grade on my exam. 

In each of these situations, you’re making a guess on how an independent variable (sleep, time, or studying) will affect a dependent variable (the amount of work you can do, making it to a party on time, or getting better grades). 

You may still be asking, “What is an example of a hypothesis used in scientific research?” Take one of the hypothesis examples from a real-world study on whether using technology before bed affects children’s sleep patterns. The hypothesis read s:

“We hypothesized that increased hours of tablet- and phone-based screen time at bedtime would be inversely correlated with sleep quality and child attention.”

It might not look like it, but this is an if-then statement. The researchers basically said, “If children have more screen usage at bedtime, then their quality of sleep and attention will be worse.” The sleep quality and attention are the dependent variables and the screen usage is the independent variable. (Usually, the independent variable comes after the “if” and the dependent variable comes after the “then,” as it is the independent variable that affects the dependent variable.) This is an excellent example of how flexible hypothesis statements can be, as long as the general idea of “if-then” and the independent and dependent variables are present.

#2: Null Hypotheses

Your if-then hypothesis is not the only one needed to complete a successful experiment, however. You also need a null hypothesis to test it against. In its most basic form, the null hypothesis is the opposite of your if-then hypothesis . When you write your null hypothesis, you are writing a hypothesis that suggests that your guess is not true, and that the independent and dependent variables have no relationship .

One null hypothesis for the cell phone and sleep study from the last section might say: 

“If children have more screen usage at bedtime, their quality of sleep and attention will not be worse.” 

In this case, this is a null hypothesis because it’s asking the opposite of the original thesis! 

Conversely, if your if-then hypothesis suggests that your two variables have no relationship, then your null hypothesis would suggest that there is one. So, pretend that there is a study that is asking the question, “Does the amount of followers on Instagram influence how long people spend on the app?” The independent variable is the amount of followers, and the dependent variable is the time spent. But if you, as the researcher, don’t think there is a relationship between the number of followers and time spent, you might write an if-then hypothesis that reads:

“If people have many followers on Instagram, they will not spend more time on the app than people who have less.”

In this case, the if-then suggests there isn’t a relationship between the variables. In that case, one of the null hypothesis examples might say:

“If people have many followers on Instagram, they will spend more time on the app than people who have less.”

You then test both the if-then and the null hypothesis to gauge if there is a relationship between the variables, and if so, how much of a relationship. 

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4 Tips to Write the Best Hypothesis

If you’re going to take the time to hold an experiment, whether in school or by yourself, you’re also going to want to take the time to make sure your hypothesis is a good one. The best hypotheses have four major elements in common: plausibility, defined concepts, observability, and general explanation.

#1: Plausibility

At first glance, this quality of a hypothesis might seem obvious. When your hypothesis is plausible, that means it’s possible given what we know about science and general common sense. However, improbable hypotheses are more common than you might think. 

Imagine you’re studying weight gain and television watching habits. If you hypothesize that people who watch more than  twenty hours of television a week will gain two hundred pounds or more over the course of a year, this might be improbable (though it’s potentially possible). Consequently, c ommon sense can tell us the results of the study before the study even begins.

Improbable hypotheses generally go against  science, as well. Take this hypothesis example: 

“If a person smokes one cigarette a day, then they will have lungs just as healthy as the average person’s.” 

This hypothesis is obviously untrue, as studies have shown again and again that cigarettes negatively affect lung health. You must be careful that your hypotheses do not reflect your own personal opinion more than they do scientifically-supported findings. This plausibility points to the necessity of research before the hypothesis is written to make sure that your hypothesis has not already been disproven.

#2: Defined Concepts

The more advanced you are in your studies, the more likely that the terms you’re using in your hypothesis are specific to a limited set of knowledge. One of the hypothesis testing examples might include the readability of printed text in newspapers, where you might use words like “kerning” and “x-height.” Unless your readers have a background in graphic design, it’s likely that they won’t know what you mean by these terms. Thus, it’s important to either write what they mean in the hypothesis itself or in the report before the hypothesis.

Here’s what we mean. Which of the following sentences makes more sense to the common person?

If the kerning is greater than average, more words will be read per minute.

If the space between letters is greater than average, more words will be read per minute.

For people reading your report that are not experts in typography, simply adding a few more words will be helpful in clarifying exactly what the experiment is all about. It’s always a good idea to make your research and findings as accessible as possible. 

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Good hypotheses ensure that you can observe the results. 

#3: Observability

In order to measure the truth or falsity of your hypothesis, you must be able to see your variables and the way they interact. For instance, if your hypothesis is that the flight patterns of satellites affect the strength of certain television signals, yet you don’t have a telescope to view the satellites or a television to monitor the signal strength, you cannot properly observe your hypothesis and thus cannot continue your study.

Some variables may seem easy to observe, but if you do not have a system of measurement in place, you cannot observe your hypothesis properly. Here’s an example: if you’re experimenting on the effect of healthy food on overall happiness, but you don’t have a way to monitor and measure what “overall happiness” means, your results will not reflect the truth. Monitoring how often someone smiles for a whole day is not reasonably observable, but having the participants state how happy they feel on a scale of one to ten is more observable. 

In writing your hypothesis, always keep in mind how you'll execute the experiment.

#4: Generalizability 

Perhaps you’d like to study what color your best friend wears the most often by observing and documenting the colors she wears each day of the week. This might be fun information for her and you to know, but beyond you two, there aren’t many people who could benefit from this experiment. When you start an experiment, you should note how generalizable your findings may be if they are confirmed. Generalizability is basically how common a particular phenomenon is to other people’s everyday life.

Let’s say you’re asking a question about the health benefits of eating an apple for one day only, you need to realize that the experiment may be too specific to be helpful. It does not help to explain a phenomenon that many people experience. If you find yourself with too specific of a hypothesis, go back to asking the big question: what is it that you want to know, and what do you think will happen between your two variables?

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Hypothesis Testing Examples

We know it can be hard to write a good hypothesis unless you’ve seen some good hypothesis examples. We’ve included four hypothesis examples based on some made-up experiments. Use these as templates or launch pads for coming up with your own hypotheses.

Experiment #1: Students Studying Outside (Writing a Hypothesis)

You are a student at PrepScholar University. When you walk around campus, you notice that, when the temperature is above 60 degrees, more students study in the quad. You want to know when your fellow students are more likely to study outside. With this information, how do you make the best hypothesis possible?

You must remember to make additional observations and do secondary research before writing your hypothesis. In doing so, you notice that no one studies outside when it’s 75 degrees and raining, so this should be included in your experiment. Also, studies done on the topic beforehand suggested that students are more likely to study in temperatures less than 85 degrees. With this in mind, you feel confident that you can identify your variables and write your hypotheses:

If-then: “If the temperature in Fahrenheit is less than 60 degrees, significantly fewer students will study outside.”

Null: “If the temperature in Fahrenheit is less than 60 degrees, the same number of students will study outside as when it is more than 60 degrees.”

These hypotheses are plausible, as the temperatures are reasonably within the bounds of what is possible. The number of people in the quad is also easily observable. It is also not a phenomenon specific to only one person or at one time, but instead can explain a phenomenon for a broader group of people.

To complete this experiment, you pick the month of October to observe the quad. Every day (except on the days where it’s raining)from 3 to 4 PM, when most classes have released for the day, you observe how many people are on the quad. You measure how many people come  and how many leave. You also write down the temperature on the hour. 

After writing down all of your observations and putting them on a graph, you find that the most students study on the quad when it is 70 degrees outside, and that the number of students drops a lot once the temperature reaches 60 degrees or below. In this case, your research report would state that you accept or “failed to reject” your first hypothesis with your findings.

Experiment #2: The Cupcake Store (Forming a Simple Experiment)

Let’s say that you work at a bakery. You specialize in cupcakes, and you make only two colors of frosting: yellow and purple. You want to know what kind of customers are more likely to buy what kind of cupcake, so you set up an experiment. Your independent variable is the customer’s gender, and the dependent variable is the color of the frosting. What is an example of a hypothesis that might answer the question of this study?

Here’s what your hypotheses might look like: 

If-then: “If customers’ gender is female, then they will buy more yellow cupcakes than purple cupcakes.”

Null: “If customers’ gender is female, then they will be just as likely to buy purple cupcakes as yellow cupcakes.”

This is a pretty simple experiment! It passes the test of plausibility (there could easily be a difference), defined concepts (there’s nothing complicated about cupcakes!), observability (both color and gender can be easily observed), and general explanation ( this would potentially help you make better business decisions ).

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Experiment #3: Backyard Bird Feeders (Integrating Multiple Variables and Rejecting the If-Then Hypothesis)

While watching your backyard bird feeder, you realized that different birds come on the days when you change the types of seeds. You decide that you want to see more cardinals in your backyard, so you decide to see what type of food they like the best and set up an experiment. 

However, one morning, you notice that, while some cardinals are present, blue jays are eating out of your backyard feeder filled with millet. You decide that, of all of the other birds, you would like to see the blue jays the least. This means you'll have more than one variable in your hypothesis. Your new hypotheses might look like this: 

If-then: “If sunflower seeds are placed in the bird feeders, then more cardinals will come than blue jays. If millet is placed in the bird feeders, then more blue jays will come than cardinals.”

Null: “If either sunflower seeds or millet are placed in the bird, equal numbers of cardinals and blue jays will come.”

Through simple observation, you actually find that cardinals come as often as blue jays when sunflower seeds or millet is in the bird feeder. In this case, you would reject your “if-then” hypothesis and “fail to reject” your null hypothesis . You cannot accept your first hypothesis, because it’s clearly not true. Instead you found that there was actually no relation between your different variables. Consequently, you would need to run more experiments with different variables to see if the new variables impact the results.

Experiment #4: In-Class Survey (Including an Alternative Hypothesis)

You’re about to give a speech in one of your classes about the importance of paying attention. You want to take this opportunity to test a hypothesis you’ve had for a while: 

If-then: If students sit in the first two rows of the classroom, then they will listen better than students who do not.

Null: If students sit in the first two rows of the classroom, then they will not listen better or worse than students who do not.

You give your speech and then ask your teacher if you can hand out a short survey to the class. On the survey, you’ve included questions about some of the topics you talked about. When you get back the results, you’re surprised to see that not only do the students in the first two rows not pay better attention, but they also scored worse than students in other parts of the classroom! Here, both your if-then and your null hypotheses are not representative of your findings. What do you do?

This is when you reject both your if-then and null hypotheses and instead create an alternative hypothesis . This type of hypothesis is used in the rare circumstance that neither of your hypotheses is able to capture your findings . Now you can use what you’ve learned to draft new hypotheses and test again! 

Key Takeaways: Hypothesis Writing

The more comfortable you become with writing hypotheses, the better they will become. The structure of hypotheses is flexible and may need to be changed depending on what topic you are studying. The most important thing to remember is the purpose of your hypothesis and the difference between the if-then and the null . From there, in forming your hypothesis, you should constantly be asking questions, making observations, doing secondary research, and considering your variables. After you have written your hypothesis, be sure to edit it so that it is plausible, clearly defined, observable, and helpful in explaining a general phenomenon.

Writing a hypothesis is something that everyone, from elementary school children competing in a science fair to professional scientists in a lab, needs to know how to do. Hypotheses are vital in experiments and in properly executing the scientific method . When done correctly, hypotheses will set up your studies for success and help you to understand the world a little better, one experiment at a time.

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What’s Next?

If you’re studying for the science portion of the ACT, there’s definitely a lot you need to know. We’ve got the tools to help, though! Start by checking out our ultimate study guide for the ACT Science subject test. Once you read through that, be sure to download our recommended ACT Science practice tests , since they’re one of the most foolproof ways to improve your score. (And don’t forget to check out our expert guide book , too.)

If you love science and want to major in a scientific field, you should start preparing in high school . Here are the science classes you should take to set yourself up for success.

If you’re trying to think of science experiments you can do for class (or for a science fair!), here’s a list of 37 awesome science experiments you can do at home

Need more help with this topic? Check out Tutorbase!

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Ashley Sufflé Robinson has a Ph.D. in 19th Century English Literature. As a content writer for PrepScholar, Ashley is passionate about giving college-bound students the in-depth information they need to get into the school of their dreams.

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What is Hypothesis? Definition, Meaning, Characteristics, Sources

  • Post last modified: 10 January 2022
  • Reading time: 18 mins read
  • Post category: Research Methodology
  • What is Hypothesis?

Hypothesis is a prediction of the outcome of a study. Hypotheses are drawn from theories and research questions or from direct observations. In fact, a research problem can be formulated as a hypothesis. To test the hypothesis we need to formulate it in terms that can actually be analysed with statistical tools.

As an example, if we want to explore whether using a specific teaching method at school will result in better school marks (research question), the hypothesis could be that the mean school marks of students being taught with that specific teaching method will be higher than of those being taught using other methods.

In this example, we stated a hypothesis about the expected differences between groups. Other hypotheses may refer to correlations between variables.

Table of Content

  • 1 What is Hypothesis?
  • 2 Hypothesis Definition
  • 3 Meaning of Hypothesis
  • 4.1 Conceptual Clarity
  • 4.2 Need of empirical referents
  • 4.3 Hypothesis should be specific
  • 4.4 Hypothesis should be within the ambit of the available research techniques
  • 4.5 Hypothesis should be consistent with the theory
  • 4.6 Hypothesis should be concerned with observable facts and empirical events
  • 4.7 Hypothesis should be simple
  • 5.1 Observation
  • 5.2 Analogies
  • 5.4 State of Knowledge
  • 5.5 Culture
  • 5.6 Continuity of Research
  • 6.1 Null Hypothesis
  • 6.2 Alternative Hypothesis

Thus, to formulate a hypothesis, we need to refer to the descriptive statistics (such as the mean final marks), and specify a set of conditions about these statistics (such as a difference between the means, or in a different example, a positive or negative correlation). The hypothesis we formulate applies to the population of interest.

The null hypothesis makes a statement that no difference exists (see Pyrczak, 1995, pp. 75-84).

Hypothesis Definition

A hypothesis is ‘a guess or supposition as to the existence of some fact or law which will serve to explain a connection of facts already known to exist.’ – J. E. Creighton & H. R. Smart

Hypothesis is ‘a proposition not known to be definitely true or false, examined for the sake of determining the consequences which would follow from its truth.’ – Max Black

Hypothesis is ‘a proposition which can be put to a test to determine validity and is useful for further research.’ – W. J. Goode and P. K. Hatt

A hypothesis is a proposition, condition or principle which is assumed, perhaps without belief, in order to draw out its logical consequences and by this method to test its accord with facts which are known or may be determined. – Webster’s New International Dictionary of the English Language (1956)

Meaning of Hypothesis

From the above mentioned definitions of hypothesis, its meaning can be explained in the following ways.

  • At the primary level, a hypothesis is the possible and probable explanation of the sequence of happenings or data.
  • Sometimes, hypothesis may emerge from an imagination, common sense or a sudden event.
  • Hypothesis can be a probable answer to the research problem undertaken for study. 4. Hypothesis may not always be true. It can get disproven. In other words, hypothesis need not always be a true proposition.
  • Hypothesis, in a sense, is an attempt to present the interrelations that exist in the available data or information.
  • Hypothesis is not an individual opinion or community thought. Instead, it is a philosophical means which is to be used for research purpose. Hypothesis is not to be considered as the ultimate objective; rather it is to be taken as the means of explaining scientifically the prevailing situation.

The concept of hypothesis can further be explained with the help of some examples. Lord Keynes, in his theory of national income determination, made a hypothesis about the consumption function. He stated that the consumption expenditure of an individual or an economy as a whole is dependent on the level of income and changes in a certain proportion.

Later, this proposition was proved in the statistical research carried out by Prof. Simon Kuznets. Matthus, while studying the population, formulated a hypothesis that population increases faster than the supply of food grains. Population studies of several countries revealed that this hypothesis is true.

Validation of the Malthus’ hypothesis turned it into a theory and when it was tested in many other countries it became the famous Malthus’ Law of Population. It thus emerges that when a hypothesis is tested and proven, it becomes a theory. The theory, when found true in different times and at different places, becomes the law. Having understood the concept of hypothesis, few hypotheses can be formulated in the areas of commerce and economics.

  • Population growth moderates with the rise in per capita income.
  • Sales growth is positively linked with the availability of credit.
  • Commerce education increases the employability of the graduate students.
  • High rates of direct taxes prompt people to evade taxes.
  • Good working conditions improve the productivity of employees.
  • Advertising is the most effecting way of promoting sales than any other scheme.
  • Higher Debt-Equity Ratio increases the probability of insolvency.
  • Economic reforms in India have made the public sector banks more efficient and competent.
  • Foreign direct investment in India has moved in those sectors which offer higher rate of profit.
  • There is no significant association between credit rating and investment of fund.

Characteristics of Hypothesis

Not all the hypotheses are good and useful from the point of view of research. It is only a few hypotheses satisfying certain criteria that are good, useful and directive in the research work undertaken. The characteristics of such a useful hypothesis can be listed as below:

Conceptual Clarity

Need of empirical referents, hypothesis should be specific, hypothesis should be within the ambit of the available research techniques, hypothesis should be consistent with the theory, hypothesis should be concerned with observable facts and empirical events, hypothesis should be simple.

The concepts used while framing hypothesis should be crystal clear and unambiguous. Such concepts must be clearly defined so that they become lucid and acceptable to everyone. How are the newly developed concepts interrelated and how are they linked with the old one is to be very clear so that the hypothesis framed on their basis also carries the same clarity.

A hypothesis embodying unclear and ambiguous concepts can to a great extent undermine the successful completion of the research work.

A hypothesis can be useful in the research work undertaken only when it has links with some empirical referents. Hypothesis based on moral values and ideals are useless as they cannot be tested. Similarly, hypothesis containing opinions as good and bad or expectation with respect to something are not testable and therefore useless.

For example, ‘current account deficit can be lowered if people change their attitude towards gold’ is a hypothesis encompassing expectation. In case of such a hypothesis, the attitude towards gold is something which cannot clearly be described and therefore a hypothesis which embodies such an unclean thing cannot be tested and proved or disproved. In short, the hypothesis should be linked with some testable referents.

For the successful conduction of research, it is necessary that the hypothesis is specific and presented in a precise manner. Hypothesis which is general, too ambitious and grandiose in scope is not to be made as such hypothesis cannot be easily put to test. A hypothesis is to be based on such concepts which are precise and empirical in nature. A hypothesis should give a clear idea about the indicators which are to be used.

For example, a hypothesis that economic power is increasingly getting concentrated in a few hands in India should enable us to define the concept of economic power. It should be explicated in terms of measurable indicator like income, wealth, etc. Such specificity in the formulation of a hypothesis ensures that the research is practicable and significant.

While framing the hypothesis, the researcher should be aware of the available research techniques and should see that the hypothesis framed is testable on the basis of them. In other words, a hypothesis should be researchable and for this it is important that a due thought has been given to the methods and techniques which can be used to measure the concepts and variables embodied in the hypothesis.

It does not however mean that hypotheses which are not testable with the available techniques of research are not to be made. If the problem is too significant and therefore the hypothesis framed becomes too ambitious and complex, it’s testing becomes possible with the development of new research techniques or the hypothesis itself leads to the development of new research techniques.

A hypothesis must be related to the existing theory or should have a theoretical orientation. The growth of knowledge takes place in the sequence of facts, hypothesis, theory and law or principles. It means the hypothesis should have a correspondence with the existing facts and theory.

If the hypothesis is related to some theory, the research work will enable us to support, modify or refute the existing theory. Theoretical orientation of the hypothesis ensures that it becomes scientifically useful. According to Prof. Goode and Prof. Hatt, research work can contribute to the existing knowledge only when the hypothesis is related with some theory.

This enables us to explain the observed facts and situations and also verify the framed hypothesis. In the words of Prof. Cohen and Prof. Nagel, “hypothesis must be formulated in such a manner that deduction can be made from it and that consequently a decision can be reached as to whether it does or does not explain the facts considered.”

If the research work based on a hypothesis is to be successful, it is necessary that the later is as simple and easy as possible. An ambition of finding out something new may lead the researcher to frame an unrealistic and unclear hypothesis. Such a temptation is to be avoided. Framing a simple, easy and testable hypothesis requires that the researcher is well acquainted with the related concepts.

Sources of Hypothesis

Hypotheses can be derived from various sources. Some of the sources is given below:

Observation

State of knowledge, continuity of research.

Hypotheses can be derived from observation from the observation of price behavior in a market. For example the relationship between the price and demand for an article is hypothesized.

Analogies are another source of useful hypotheses. Julian Huxley has pointed out that casual observations in nature or in the framework of another science may be a fertile source of hypotheses. For example, the hypotheses that similar human types or activities may be found in similar geophysical regions come from plant ecology.

This is one of the main sources of hypotheses. It gives direction to research by stating what is known logical deduction from theory lead to new hypotheses. For example, profit / wealth maximization is considered as the goal of private enterprises. From this assumption various hypotheses are derived’.

An important source of hypotheses is the state of knowledge in any particular science where formal theories exist hypotheses can be deduced. If the hypotheses are rejected theories are scarce hypotheses are generated from conception frameworks.

Another source of hypotheses is the culture on which the researcher was nurtured. Western culture has induced the emergence of sociology as an academic discipline over the past decade, a large part of the hypotheses on American society examined by researchers were connected with violence. This interest is related to the considerable increase in the level of violence in America.

The continuity of research in a field itself constitutes an important source of hypotheses. The rejection of some hypotheses leads to the formulation of new ones capable of explaining dependent variables in subsequent research on the same subject.

Null and Alternative Hypothesis

Null hypothesis.

The hypothesis that are proposed with the intent of receiving a rejection for them are called Null Hypothesis . This requires that we hypothesize the opposite of what is desired to be proved. For example, if we want to show that sales and advertisement expenditure are related, we formulate the null hypothesis that they are not related.

Similarly, if we want to conclude that the new sales training programme is effective, we formulate the null hypothesis that the new training programme is not effective, and if we want to prove that the average wages of skilled workers in town 1 is greater than that of town 2, we formulate the null hypotheses that there is no difference in the average wages of the skilled workers in both the towns.

Since we hypothesize that sales and advertisement are not related, new training programme is not effective and the average wages of skilled workers in both the towns are equal, we call such hypotheses null hypotheses and denote them as H 0 .

Alternative Hypothesis

Rejection of null hypotheses leads to the acceptance of alternative hypothesis . The rejection of null hypothesis indicates that the relationship between variables (e.g., sales and advertisement expenditure) or the difference between means (e.g., wages of skilled workers in town 1 and town 2) or the difference between proportions have statistical significance and the acceptance of the null hypotheses indicates that these differences are due to chance.

As already mentioned, the alternative hypotheses specify that values/relation which the researcher believes hold true. The alternative hypotheses can cover a whole range of values rather than a single point. The alternative hypotheses are denoted by H 1 .

Business Ethics

( Click on Topic to Read )

  • What is Ethics?
  • What is Business Ethics?
  • Values, Norms, Beliefs and Standards in Business Ethics
  • Indian Ethos in Management
  • Ethical Issues in Marketing
  • Ethical Issues in HRM
  • Ethical Issues in IT
  • Ethical Issues in Production and Operations Management
  • Ethical Issues in Finance and Accounting
  • What is Corporate Governance?
  • What is Ownership Concentration?
  • What is Ownership Composition?
  • Types of Companies in India
  • Internal Corporate Governance
  • External Corporate Governance
  • Corporate Governance in India
  • What is Enterprise Risk Management (ERM)?
  • What is Assessment of Risk?
  • What is Risk Register?
  • Risk Management Committee

Corporate social responsibility (CSR)

  • Theories of CSR
  • Arguments Against CSR
  • Business Case for CSR
  • Importance of CSR in India
  • Drivers of Corporate Social Responsibility
  • Developing a CSR Strategy
  • Implement CSR Commitments
  • CSR Marketplace
  • CSR at Workplace
  • Environmental CSR
  • CSR with Communities and in Supply Chain
  • Community Interventions
  • CSR Monitoring
  • CSR Reporting
  • Voluntary Codes in CSR
  • What is Corporate Ethics?

Lean Six Sigma

  • What is Six Sigma?
  • What is Lean Six Sigma?
  • Value and Waste in Lean Six Sigma
  • Six Sigma Team
  • MAIC Six Sigma
  • Six Sigma in Supply Chains
  • What is Binomial, Poisson, Normal Distribution?
  • What is Sigma Level?
  • What is DMAIC in Six Sigma?
  • What is DMADV in Six Sigma?
  • Six Sigma Project Charter
  • Project Decomposition in Six Sigma
  • Critical to Quality (CTQ) Six Sigma
  • Process Mapping Six Sigma
  • Flowchart and SIPOC
  • Gage Repeatability and Reproducibility
  • Statistical Diagram
  • Lean Techniques for Optimisation Flow
  • Failure Modes and Effects Analysis (FMEA)
  • What is Process Audits?
  • Six Sigma Implementation at Ford
  • IBM Uses Six Sigma to Drive Behaviour Change
  • Research Methodology
  • What is Research?

Sampling Method

Research methods.

  • Data Collection in Research
  • Methods of Collecting Data
  • Application of Business Research
  • Levels of Measurement
  • What is Sampling?
  • Hypothesis Testing

Research Report

  • What is Management?
  • Planning in Management
  • Decision Making in Management
  • What is Controlling?
  • What is Coordination?
  • What is Staffing?
  • Organization Structure
  • What is Departmentation?
  • Span of Control
  • What is Authority?
  • Centralization vs Decentralization
  • Organizing in Management
  • Schools of Management Thought
  • Classical Management Approach
  • Is Management an Art or Science?
  • Who is a Manager?

Operations Research

  • What is Operations Research?
  • Operation Research Models
  • Linear Programming
  • Linear Programming Graphic Solution
  • Linear Programming Simplex Method
  • Linear Programming Artificial Variable Technique
  • Duality in Linear Programming
  • Transportation Problem Initial Basic Feasible Solution
  • Transportation Problem Finding Optimal Solution
  • Project Network Analysis with Critical Path Method
  • Project Network Analysis Methods
  • Project Evaluation and Review Technique (PERT)
  • Simulation in Operation Research
  • Replacement Models in Operation Research

Operation Management

  • What is Strategy?
  • What is Operations Strategy?
  • Operations Competitive Dimensions
  • Operations Strategy Formulation Process
  • What is Strategic Fit?
  • Strategic Design Process
  • Focused Operations Strategy
  • Corporate Level Strategy
  • Expansion Strategies
  • Stability Strategies
  • Retrenchment Strategies
  • Competitive Advantage
  • Strategic Choice and Strategic Alternatives
  • What is Production Process?
  • What is Process Technology?
  • What is Process Improvement?
  • Strategic Capacity Management
  • Production and Logistics Strategy
  • Taxonomy of Supply Chain Strategies
  • Factors Considered in Supply Chain Planning
  • Operational and Strategic Issues in Global Logistics
  • Logistics Outsourcing Strategy
  • What is Supply Chain Mapping?
  • Supply Chain Process Restructuring
  • Points of Differentiation
  • Re-engineering Improvement in SCM
  • What is Supply Chain Drivers?
  • Supply Chain Operations Reference (SCOR) Model
  • Customer Service and Cost Trade Off
  • Internal and External Performance Measures
  • Linking Supply Chain and Business Performance
  • Netflix’s Niche Focused Strategy
  • Disney and Pixar Merger
  • Process Planning at Mcdonald’s

Service Operations Management

  • What is Service?
  • What is Service Operations Management?
  • What is Service Design?
  • Service Design Process
  • Service Delivery
  • What is Service Quality?
  • Gap Model of Service Quality
  • Juran Trilogy
  • Service Performance Measurement
  • Service Decoupling
  • IT Service Operation
  • Service Operations Management in Different Sector

Procurement Management

  • What is Procurement Management?
  • Procurement Negotiation
  • Types of Requisition
  • RFX in Procurement
  • What is Purchasing Cycle?
  • Vendor Managed Inventory
  • Internal Conflict During Purchasing Operation
  • Spend Analysis in Procurement
  • Sourcing in Procurement
  • Supplier Evaluation and Selection in Procurement
  • Blacklisting of Suppliers in Procurement
  • Total Cost of Ownership in Procurement
  • Incoterms in Procurement
  • Documents Used in International Procurement
  • Transportation and Logistics Strategy
  • What is Capital Equipment?
  • Procurement Process of Capital Equipment
  • Acquisition of Technology in Procurement
  • What is E-Procurement?
  • E-marketplace and Online Catalogues
  • Fixed Price and Cost Reimbursement Contracts
  • Contract Cancellation in Procurement
  • Ethics in Procurement
  • Legal Aspects of Procurement
  • Global Sourcing in Procurement
  • Intermediaries and Countertrade in Procurement

Strategic Management

  • What is Strategic Management?
  • What is Value Chain Analysis?
  • Mission Statement
  • Business Level Strategy
  • What is SWOT Analysis?
  • What is Competitive Advantage?
  • What is Vision?
  • What is Ansoff Matrix?
  • Prahalad and Gary Hammel
  • Strategic Management In Global Environment
  • Competitor Analysis Framework
  • Competitive Rivalry Analysis
  • Competitive Dynamics
  • What is Competitive Rivalry?
  • Five Competitive Forces That Shape Strategy
  • What is PESTLE Analysis?
  • Fragmentation and Consolidation Of Industries
  • What is Technology Life Cycle?
  • What is Diversification Strategy?
  • What is Corporate Restructuring Strategy?
  • Resources and Capabilities of Organization
  • Role of Leaders In Functional-Level Strategic Management
  • Functional Structure In Functional Level Strategy Formulation
  • Information And Control System
  • What is Strategy Gap Analysis?
  • Issues In Strategy Implementation
  • Matrix Organizational Structure
  • What is Strategic Management Process?

Supply Chain

  • What is Supply Chain Management?
  • Supply Chain Planning and Measuring Strategy Performance
  • What is Warehousing?
  • What is Packaging?
  • What is Inventory Management?
  • What is Material Handling?
  • What is Order Picking?
  • Receiving and Dispatch, Processes
  • What is Warehouse Design?
  • What is Warehousing Costs?

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  1. Desertification

    desertification, the process by which natural or human causes reduce the biological productivity of drylands (arid and semiarid lands). Declines in productivity may be the result of climate change, deforestation, overgrazing, poverty, political instability, unsustainable irrigation practices, or combinations of these factors.

  2. What Really Turned the Sahara Desert From a Green Oasis Into a

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  3. Chapter 3 : Desertification

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  6. Darwin, evolution, & natural selection (article)

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  7. Desertion

    Desertion is the abandonment of a military duty or post without permission (a pass, liberty or leave) and is done with the intention of not returning. This contrasts with unauthorized absence ( UA ) or absence without leave ( AWOL / ˈ eɪ w ɒ l / ), which are temporary forms of absence.

  8. Desertification

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  10. Desertification, land degradation and drought

    It entered into force on 26 December 1996. Deserts are among the "fragile ecosystems" addressed by Agenda 21, and "combating desertification and drought" is the subject of Chapter 12. Desertification includes land degradation in arid, semi-arid and dry sub humid areas resulting from various factors, including climatic variations and human ...

  11. Chapter 12 Flashcards

    desertion hypothesis. states that individuals enter a job dominated by the other sex, they are more likely than other workers to leave that occupation in favor of a new one in one study 61% of women in male dominated occupations had left their job less than 30% of their male colleagues had done so half of the women switched to a female ...

  12. Desertification in the Karoo

    The landscape of the Karoo shows evidence of desertification in that systems of deep gullies and crazy-paved badlands scar much of the landscape. These are likely to have formed when vegetation ...

  13. What is a scientific hypothesis?

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  14. What is Hypothesis

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  15. Research Hypothesis In Psychology: Types, & Examples

    Examples. A research hypothesis, in its plural form "hypotheses," is a specific, testable prediction about the anticipated results of a study, established at its outset. It is a key component of the scientific method. Hypotheses connect theory to data and guide the research process towards expanding scientific understanding.

  16. Desertion Definition & Meaning

    The meaning of DESERTION is an act of deserting; especially : the abandonment without consent or legal justification of a person, post, or relationship and the associated duties and obligations. How to use desertion in a sentence.

  17. Chapter 19: Deserts and Winds Flashcards

    this dune is between isolated barchans & extensive tranverse dunes; form scalloped rows of sand oriented at right angels to the wind. longitudinal dunes. when long ridges of sand form more or less parallel to the prevailing wind where sand supplies are moderate. parabolic dunes. form where vegetation partially covers the sand, look similar to ...

  18. How to Write a Strong Hypothesis

    6. Write a null hypothesis. If your research involves statistical hypothesis testing, you will also have to write a null hypothesis. The null hypothesis is the default position that there is no association between the variables. The null hypothesis is written as H 0, while the alternative hypothesis is H 1 or H a.

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  20. What Is a Hypothesis and How Do I Write One?

    Merriam Webster defines a hypothesis as "an assumption or concession made for the sake of argument.". In other words, a hypothesis is an educated guess. Scientists make a reasonable assumption--or a hypothesis--then design an experiment to test whether it's true or not.

  21. What Is Hypothesis? Definition, Meaning, Characteristics, Sources

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  22. Soc 138 Week 10 Flashcards

    A stressful burden experienced by women in men's occupations. Tokens are accepted because of their minority status, not despite of it. They are actively discouraged from recruiting others like themselves, and become strongly wedded to organizational norms. Token recruits are hyper visible as members of a category, but invisible as individual.

  23. What is a Hypothesis

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