English

Martyn Shuttleworth915.1K reads

The null hypothesis, H_{0}, is an essential part of any research design, and is always tested, even indirectly.

Discover 18 more articles on this topic

Don't miss these related articles:

- 1Scientific Method
- 2Formulate a Question
- 3Collect Data
- 4Test Hypothesis
- 5Conclusion
- 6Overview

The simplistic definition of the null is as the opposite of the alternative hypothesis, H_{1}, although the principle is a little more complex than that.

The null hypothesis (H_{0}) is a hypothesis which the researcher tries to disprove, reject or nullify.

The 'null' often refers to the common view of something, while the alternative hypothesis is what the researcher really thinks is the cause of a phenomenon.

The simplistic definition of the null is as the opposite of the alternative hypothesis, H_{1}, although the principle is a little more complex than that.

The null hypothesis (H_{0}) is a hypothesis which the researcher tries to disprove, reject or nullify.

The 'null' often refers to the common view of something, while the alternative hypothesis is what the researcher really thinks is the cause of a phenomenon.

An experiment conclusion always refers to the null, rejecting or accepting H_{0} rather than H_{1}.

Despite this, many researchers neglect the null hypothesis when testing hypotheses, which is poor practice and can have adverse effects.

A researcher may postulate a hypothesis:

H_{1}: Tomato plants exhibit a higher rate of growth when planted in compost rather than in soil.

And a null hypothesis:

H_{0}: Tomato plants do not exhibit a higher rate of growth when planted in compost rather than soil.

It is important to carefully select the wording of the null, and ensure that it is as specific as possible. For example, the researcher might postulate a null hypothesis:

H_{0}: Tomato plants show no difference in growth rates when planted in compost rather than soil.

There is a major flaw with this H_{0}. If the plants actually grow more slowly in compost than in soil, an impasse is reached. H_{1} is not supported, but neither is H_{0}, because there is a difference in growth rates.

If the null is rejected, with no alternative, the experiment may be invalid. This is the reason why science uses a battery of deductive and inductive processes to ensure that there are no flaws in the hypotheses.

Many scientists neglect the null, assuming that it is merely the opposite of the alternative, but it is good practice to spend a little time creating a sound hypothesis. It is not possible to change any hypothesis retrospectively, including H_{0}.

If significance tests generate 95% or 99% likelihood that the results do not fit the null hypothesis, then it is rejected, in favor of the alternative.

Otherwise, the null is accepted. These are the only correct assumptions, and it is incorrect to reject, or accept, H_{1}.

Accepting the null hypothesis does not mean that it is true. It is still a hypothesis, and must conform to the principle of falsifiability, in the same way that rejecting the null does not prove the alternative.

The major problem with the H_{0} is that many researchers, and reviewers, see accepting the null as a failure of the experiment. This is very poor science, as accepting or rejecting any hypothesis is a positive result.

Even if the null is not refuted, the world of science has learned something new. Strictly speaking, the term ‘failure’, should only apply to errors in the experimental design, or incorrect initial assumptions.

The Flat Earth model was common in ancient times, such as in the civilizations of the Bronze Age or Iron Age. This may be thought of as the null hypothesis, H_{0}, at the time.

H_{0}: World is Flat

Many of the Ancient Greek philosophers assumed that the sun, moon and other objects in the universe circled around the Earth. Hellenistic astronomy established the spherical shape of the earth around 300 BC.

H_{0}: The Geocentric Model: Earth is the centre of the Universe and it is Spherical

Copernicus had an alternative hypothesis, H_{1} that the world actually circled around the sun, thus being the center of the universe. Eventually, people got convinced and accepted it as the null, H_{0}.

H_{0}: The Heliocentric Model: Sun is the centre of the universe

Later someone proposed an alternative hypothesis that the sun itself also circled around the something within the galaxy, thus creating a new H_{0}. This is how research works - the H_{0} gets closer to the reality each time, even if it isn't correct, it is better than the last H_{0}.

Full reference:

Martyn Shuttleworth (Feb 3, 2008). Null Hypothesis. Retrieved Oct 23, 2020 from Explorable.com: https://forum.explorable.com/null-hypothesis

The text in this article is licensed under the Creative Commons-License Attribution 4.0 International (CC BY 4.0).

This means you're free to copy, share and adapt any parts (or all) of the text in the article, as long as you give ** appropriate credit** and

That is it. You don't need our permission to copy the article; just include a link/reference back to this page. You can use it freely (with some kind of link), and we're also okay with people reprinting in publications like books, blogs, newsletters, course-material, papers, wikipedia and presentations (with clear attribution).

Want the full version to study at home, take to school or just scribble on?

Whether you are an academic novice, or you simply want to brush up your skills, this book will take your academic writing skills to the next level.

Download electronic versions:

- Epub for mobiles and tablets

- For Kindle here

- PDF version here

Discover 18 more articles on this topic

Don't miss these related articles:

- 1Scientific Method
- 2Formulate a Question
- 3Collect Data
- 4Test Hypothesis
- 5Conclusion
- 6Overview

Thank you to...

This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 827736.

Subscribe / Share

- Subscribe to our RSS Feed
- Like us on Facebook
- Follow us on Twitter
- Founder:
- Oskar Blakstad Blog
- Oskar Blakstad on Twitter

Explorable.com - 2008-2020

You are free to copy, share and adapt any text in the article, as long as you give *appropriate credit* and *provide a link/reference* to this page.