Use traditional method of testing hypothesis.
Researchers designed a questionnaire to identify compulsive buyers. For a sample of consumers who identified themselves as compulsive buyers, scores have a mean of 0.83 and a standard deviation of 0.24. Assume the subjects were randomly selected and that the sample size was 32. Using a 0.01 significance level, test the claim that the self-identified compulsive buyer population has a mean greater than 0.21, the mean for the general population. Does the questionnaire seem to be effective in identifying compulsive buyers?