Researchers developed a questionnaire to identify compulsive buyers. A random sample of 32 subjects who identified themselves as compulsive buyers was obtained, and they had a mean questionnaire score of 0.83 with a standard deviation of 0.24 (based on data from "A Clinical Screener for Compulsive Buying," by Faber and Guinn, Journal of Consumer Research, Vol. 19). Test the claim that the population of self-identified compulsive buyers has a mean greater than the mean of 0.21 for the general population.