An investigator measures the physiological stress levels (measured in micrograms of cortisol per deciliter, which yields interval-level data) of two independent groups of emergency workers under different shift patterns. Assuming the data meets all parametric assumptions, which of the following is the appropriate inferential test to determine whether there is a statistically significant difference between the two groups, rather than a non-parametric alternative or a descriptive statistic?
Wilcoxon Signed-Ranks test
Standard deviation
Mann-Whitney UUU test
Unrelated ttt-test
644 exam-style questions on OCR A Level Psychology Research methods and techniques. Each one has a worked solution and a mark scheme showing where the marks go.