HYPOTHESIS

HYPOTHESIS

Definition

A hypothesis is a tentative statement about the relationship between two or more variables. A hypothesis is a specific, testable prediction about what you expect to happen in your study.

For example, a study designed to look at the relationship between sleep deprivation and test performance might have a hypothesis that states, “This study is designed to assess the hypothesis that sleep deprived people will perform worse on a test than individuals who are not sleep deprived.”

TYPES OF HYPOTHESES

Null hypotheses

The null hypothesis states that there is no relationship between the two variables being studied (one variable does not affect the other). It states results are due to chance and are not significant in terms of supporting the idea being investigated.

Alternative hypotheses

The alternative hypothesis states that there is a relationship between the two variables being studied (one variable has an effect on the other). It states that results are not due to chance and that they are significant in terms of supporting the theory being investigated.

One tailed Hypothesis

one-tailed directional hypothesis predicts the nature of the effect of the independent variable on the dependent variable.

  • E.g.: Adults will correctly recall more words than children.

Two tailed Hypothesis

two-tailed non-directional hypothesis predicts that the independent variable will have an effect on the dependent variable, but the direction of the effect is not specified.

  • E.g.: There will be a difference in how many numbers are correctly recalled by children and adults.

Characteristics of a good hypothesis

ü  Hypothesis should be simple.

ü  Hypothesis should be specific.

ü  Hypothesis should be stated in advance.

Elements of a Good Hypothesis

When trying to come up with a good hypothesis for your own psychology research or experiments, ask yourself the following questions:

  • Is your hypothesis based on your research of a topic?
  • Can your hypothesis be tested?
  • Does your hypothesis include independent and dependent variables?

Before you come up with a specific hypothesis, spend some time doing background research on your topic. Once you have completed a literature review, start thinking of potential questions you still have. Pay attention to the discussion section in the journal articles you read. Many authors will suggest questions that still need to be explored.

Hypothesis

  • Needless to say, it can all be a little intimidating, and many students find this to be the most difficult stage of the scientific method.
  • It is just about making sure that you are asking the right questions and wording your hypothesis statements correctly.

HOW TO WRITE A HYPOTHESIS

The Three-Step Process

Often, it is still quite difficult to isolate a testable hypothesis after all of the research and study. The best way is to adopt a three-step hypothesis; this will help you to narrow things down, and is the most foolproof guide to how to write a hypothesis. Step one is to think of a general hypothesis, including everything that you have observed and reviewed during the information gathering stage of any research design. This stage is often called developing the research problem.

An Example of How to Write a Hypothesis

A worker on a fish-farm notices that his trout seem to have more fish lice in the summer, when the water levels are low, and wants to find out why. His research leads him to believe that the amount of oxygen is the reason – fish that are oxygen stressed tend to be more susceptible to disease and parasites.

He proposes a general hypothesis

“Water levels affect the amount of lice suffered by rainbow trout.”

This is a good general hypothesis, but it gives no guide to how to design the research or experiment. The hypothesis must be refined to give a little direction.

“Rainbow trout suffer more lice when water levels are low.”

Now there is some directionality, but the hypothesis is not really testable, so the final stage is to design an experiment around which research can be designed, a testable hypothesis.

“Rainbow trout suffer more lice in low water conditions because there is less oxygen in the water.”

This is a testable hypothesis – he has established variables, and by measuring the amount of oxygen in the water, eliminating other controlled variables, such as temperature, he can see if there is a correlation against the number of lice on the fish. This is an example of how a gradual focusing of research helps to define how to write a hypothesis.

The Next Stage – What to Do with the Hypothesis

Once you have your hypothesis, the next stage is to design the experiment, allowing a statistical analysis of data, and allowing you to test your hypothesis. The statistical analysis will allow you to reject either the null or the alternative hypothesis. If the alternative is rejected, then you need to go back and refine the initial hypothesis or design a completely new research program. This is part of the scientific process, striving for greater accuracy and developing ever more refined hypotheses.

Examples of a Good Hypothesis

A hypothesis often follows a basic format of “If {this happens} then {this will happen}.” One way to structure your hypothesis is to describe what will happen to the variable if you make changes to the independent variable.

The basic format might be:

“If {these changes are made to a certain independent variable}, then we will observe {a change in a specific dependent variable}.”

A few examples:

  • “Students who eat breakfast will perform better on a math exam than students who do not eat breakfast.”
  • “Students who experiencetest anxiety prior to an English exam will get higher scores than students who do not experience test anxiety.”
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