Pearson Edexcel · GCSE · Psychology
Course version: 1PS0 · Version from Sept 2017
Designing psychological research: 11.1.3 Be able to write a null hypothesis
A null hypothesis predicts there will be no significant difference or relationship between the variables studied, and any observed changes are due to chance.
Checked against the Pearson Edexcel 1PS0 specification (opens in a new tab) on .
- Point 3 of 17
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
A null hypothesis predicts there will be no significant difference or relationship between the variables studied, and any observed changes are due to chance. Writing a clear null hypothesis requires explicitly stating both the independent variable (IV) and the dependent variable (DV). For an experiment, it states there will be no difference in the DV between the conditions of the IV. For example, 'There will be no significant difference in the number of words recalled between participants who listen to music and those who study in silence'. For a correlational study, it states there will be no significant relationship between the two co-variables. Variables must be operationalised clearly so the hypothesis is testable and precise.
What earns the marks
- State clearly that there will be no significant difference or relationship between the variables.
- Identify and include both the independent variable and the dependent variable (or both co-variables).
- Operationalise the variables accurately based on the provided research scenario.
- Ensure the statement attributes any potential findings to chance rather than a true effect.
Common mistakes and how to put them right
Writing an alternative hypothesis instead of a null hypothesis.
Put it right: Ensure the statement explicitly predicts 'no significant difference' or 'no significant relationship'.
Failing to operationalise the variables.
Put it right: State exactly how the variables are measured, such as 'number of words recalled' rather than just 'memory'.
Omitting one of the conditions of the independent variable.
Put it right: Explicitly mention both conditions being compared, e.g., 'between the music group and the silence group'.
Exam tips
- Always start a null hypothesis for an experiment with 'There will be no significant difference in...' to ensure the correct phrasing.
- Double-check that you have included both levels of the independent variable in your statement.
- Use the exact wording from the exam scenario when operationalising your dependent variable to guarantee accuracy.
Try the lesson
The start of the Designing psychological research: 11.1.3 Be able to write a null hypothesis lesson, made from checked teaching notes for this specification point.
Have a go first
Which of the following statements best describes the standard format of a null hypothesis?
Listen
A null hypothesis predicts there will be no significant difference or relationship between the variables studied, and any observed changes are due to chance. Writing a clear null hypothesis requires explicitly stating both the independent variable (IV) and the dependent variable (DV). For an experiment, it states there will be no difference in the DV between the conditions of the IV. For example, 'There will be no significant difference in the number of words recalled between participants who listen to music and those who study in silence'. For a correlational study, it states there will be no significant relationship between the two co-variables. Variables must be operationalised clearly so the hypothesis is testable and precise. A strong answer earns marks for these points. State clearly that there will be no significant difference or relationship between the variables. Identify and include both the independent variable and the dependent variable (or both co-variables). Operationalise the variables accurately based on the provided research scenario. Ensure the statement attributes any potential findings to chance rather than a true effect. A common slip: Writing an alternative hypothesis instead of a null hypothesis. Instead, ensure the statement explicitly predicts 'no significant difference' or 'no significant relationship'. Exam tip: Always start a null hypothesis for an experiment with 'There will be no significant difference in... to ensure the correct phrasing.
Key words
Say what each word means before you turn the card.
Null hypothesis
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Operationalisation of variables
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Independent variable
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Dependent variable
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See every definition
- Null hypothesis
- A prediction that there will be no significant difference or relationship between the variables studied, and any observed changes are due to chance.
- Operationalisation of variables
- Stating exactly how the variables are measured so the hypothesis is testable and precise, such as 'number of words recalled' rather than just 'memory'.
- Independent variable
- The variable whose conditions are compared, and both of its conditions must be explicitly mentioned in the null hypothesis.
- Dependent variable
- The variable in which no difference is predicted between the conditions of the independent variable, and it must be operationalised clearly.
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