A clinical psychologist conducts an experiment to test if a new mindfulness program reduces stress scores. The psychologist finds a statistically significant reduction in stress (p<0.05p < 0.05p<0.05) and consequently rejects the null hypothesis. In reality, the mindfulness program has no genuine effect on stress, and the observed difference was entirely due to random sampling variation.
Which of the following statements correctly identifies and explains the error committed by the psychologist?
A Type II error, because they retained a null hypothesis that is actually false.
A Type II error, because they rejected a null hypothesis that is actually true.
A Type I error, because they rejected a null hypothesis that is actually true.
A Type I error, because they retained a null hypothesis that is actually false.
513 exam-style questions on OCR A Level Psychology Data recording, analysis and presentation. Each one has a worked solution and a mark scheme showing where the marks go.