The American Statistical Association conducts salary surveys of its members. The results are published and are also available at the ASA website http://www.amstat.org/profession/salarysurvey.pdf. Assume that you want to analyze the variability in the salary of full professors at research universities and you want to see how the variability changes over time (i.e., over surveys). The individual salaries are not given, however, so a variance or standard deviation could not be computed. Furthermore, the class intervals (i.e., for the number of years at the rank of full professor) are unequal and the last class is open-ended (e.g., 33 or more years). The frequencies of each class are given, in addition to, Q1, Q2, and Q3. Given this limited information, how would you compare the variability in the salaries over time?