The Southern Economic Journal (Apr. 2008) published a guide to graduate study in economics by ranking the Ph.D. programs at 129 colleges and universities. Each program was evaluated according to the number of publications published by faculty teaching in the Ph.D. program and by the quality of the publications. Data obtained from the Social Science Citation Index (SSCI) were used to calculate an overall productivity score for each Ph.D. program. The mean and standard deviation of these 129 productivity scores were then used to compute a z-score for each economics program. Harvard University had the highest z-score (z = 5.08) and, hence, was the top-ranked school; Howard University was ranked last since it had the lowest z-score (z = -0.81). The data (z-scores) for all 129 economic programs are saved in the ECOPHD file.
a. Interpret the z-score for Harvard University.
b. Interpret the z-score for Howard University.
c. The authors of the Southern Economic Journal article note that "only 44 of the 129 schools have positive z-scores, indicating that the distribution of overall productivity is skewed to the right." Do you agree? (Check your answer by constructing a histogram for the z-scores in the ECOPHD file.)