A-Level Psychology: Research Methods — Statistics and Test Choice

At least a tenth of the marks in A-level Psychology require mathematical skills, and a quarter or more assess research methods, so statistics is not an optional extra. This material trains the inferential testing and data-handling skills named in the research methods section of current specifications (for example AQA's A-level Psychology for first teaching from September 2025), with every question carrying its own data.

The quiz starts with a full sign test: you work out N by removing a 'no change' score, identify S as the less frequent sign and compare it with a short extract of critical values to decide whether the result is significant. Four questions then practise test choice, the skill most often tested in short-answer questions: you decide whether a study looks for a difference or a correlation, whether the design is related or unrelated and what the level of measurement is, and choose between Spearman's rho, the unrelated t-test, the Wilcoxon test and the chi-squared test, with Pearson's r, Mann-Whitney, the related t-test and the sign test as alternatives.

Further questions cover levels of measurement (including why rating scales are treated as ordinal), choosing and calculating the median when an outlier distorts the mean, calculating a percentage from observation data, directional hypotheses and one-tailed tests, the meaning of p ≤ 0.05, the trade-off that makes a strict significance level produce Type II errors, the strength of correlation coefficients and the rule for which tests need a calculated value below the critical value.

The material offers four formats. The 12-question quiz gives a worked explanation after every answer. The 18 flashcards hold the test-choice table, the parametric criteria and the key definitions. The printable written work sets eight open tasks with ruled space for handwritten answers that are then checked: a complete sign test from raw scores, justifying a test choice, calculating a mean to two decimal places, working with percentages from a content analysis, interpreting standard deviations and explaining why 0.05 is the usual significance level. In the oral exam, an examiner gives you short study descriptions one at a time, asks you to choose and justify tests, and gives precise feedback at the end.

It is designed for the maths-heavy questions on the research methods paper and for any topic where you must interpret a results table.

• Choose between the sign test, Wilcoxon, Mann-Whitney, related and unrelated t-tests, Spearman's rho, Pearson's r and chi-squared, and justify the choice
• Calculate the sign test and use a table of critical values to decide on significance
• Explain probability and significance, one-tailed and two-tailed tests, and Type I and Type II errors
• Identify nominal, ordinal and interval data
• Calculate the mean, median and percentages, and choose an appropriate measure of central tendency
• Interpret correlation coefficients and measures of dispersion

Practice material written by Zestly, based on the research methods content of A-level Psychology specifications (for example AQA A-level Psychology 7182, specification for first teaching from September 2025: 4.2.3.2 Data handling and analysis, 4.2.3.3 Inferential testing, and the mathematical requirements annex). Critical values quoted in the questions were computed from the binomial distribution.