A clinical psychologist wanted to investigate whether there was a correlation between the daily duration of compulsive handwashing (measured in minutes) and cortisol levels in saliva (measured in nanograms per millilitre) in patients diagnosed with obsessive-compulsive disorder (OCD). The psychologist formulated a directional hypothesis and collected data from 18 participants with OCD.
The psychologist decided to use Pearson's r r\,r test to analyse the data because they were looking for a relationship between two co-variables.
Explain one other reason why the psychologist used Pearson's r r\,r test in this study.
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.