An occupational psychologist wants to investigate whether there is a significant difference in perceived stress levels between employees in different departments at a large corporation. The researcher collects data from two independent groups of volunteers:
Each participant completes a standardized self-report questionnaire that produces a stress-level score on an ordinal scale from 1 (extremely relaxed) to 50 (extremely stressed).
The psychologist wants to perform an inferential statistical test to determine whether there is a significant difference in stress-level scores between the two departments.
Explain why a Mann-Whitney test is an appropriate choice of statistical test in this situation and a Spearman's test is not.
121 exam-style questions on AQA A Level Psychology Inferential testing (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.