What does the AQA Research methods topic cover?

Research methods (4.7) covers experimental methods (lab, field, natural, quasi) and design (independent groups, repeated measures, matched pairs), observational techniques, self-report techniques (questionnaires and interviews), correlations, sampling methods, data handling and descriptive statistics (central tendency, dispersion, distributions), and inferential testing (significance, the sign test, type I and II errors, choosing a test).

What is the difference between an extraneous and a confounding variable?

An extraneous variable is any variable other than the independent variable that could affect the dependent variable and should be controlled. A confounding variable is one that varies systematically with the independent variable, so it changes alongside it and confounds the results, making it impossible to know what caused the effect.

What are the three experimental designs?

Independent groups (different participants in each condition, no order effects but participant variables differ), repeated measures (the same participants in all conditions, controlling participant variables but creating order effects, reduced by counterbalancing) and matched pairs (different but matched participants, reducing both problems but with difficult, imperfect matching).

When do you use the sign test?

The sign test is used when you are testing for a difference (not a correlation), using a repeated measures or related design, with nominal (categorical) data. You calculate the value of S and compare it with a critical value from a table to decide whether the result is significant at p less than 0.05.

What is the difference between a type I and type II error?

A type I error is rejecting a true null hypothesis (a false positive), more likely if the significance level is too lenient. A type II error is accepting a false null hypothesis (a false negative), more likely if the significance level is too strict. The 0.05 level balances these risks.

How is Research methods assessed in the exams?

Research methods is examined across all three papers, with a major presence in Paper 2 and substantial maths content (at least 10% of total marks). Expect questions on designing studies, identifying variables, choosing methods and tests, and calculating and interpreting statistics. Practise the maths until it is automatic.

EnglandPsychology

AQA A-Level Psychology 4.7 Research methods: experiments, sampling and statistics

A complete AQA A-Level Psychology guide to module 4.7 Research methods. Covers experimental methods and design, observations, self-report, correlations, sampling, data handling and descriptive statistics, and inferential testing.

Generated by Claude Opus 4.818 min read4.7Updated 2026-06-02

Reviewed by: AI editorial process; not yet individually human-reviewed

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What module 4.7 demands
Designing and gathering data
Analysing data
Check your knowledge

What module 4.7 demands

Research methods is the methodological backbone of the whole qualification, examined across all three papers with a heavy maths element. It covers how psychologists design studies, gather data, sample participants, describe data and test for significance. The examiners reward precise method choices, correct variable identification, and confident statistics.

Designing and gathering data

Experimental methods (lab, field, natural, quasi) test cause and effect using an IV and DV that must be operationalised, while controlling extraneous and confounding variables. Experimental design (independent groups, repeated measures, matched pairs) is managed with randomisation and counterbalancing. Observations, self-report (questionnaires and interviews) and correlations offer alternatives, and sampling (random, systematic, stratified, opportunity, volunteer) affects representativeness.

Analysing data

Data handling covers quantitative and qualitative data, central tendency (mean, median, mode), dispersion (range, standard deviation) and distributions. Inferential testing uses probability and significance (p less than 0.05), critical values, type I and type II errors, the sign test, and rules for choosing a test based on the design, the aim (difference or correlation) and the level of measurement.

Check your knowledge

Distinguish between an independent and a dependent variable. (2 marks)
Explain one strength of a repeated measures design. (2 marks)
Describe how to obtain a stratified sample. (3 marks)
State when the sign test should be used. (3 marks)

Sources & how we know this

AQA A-level Psychology (7182) specification — AQA (2015)