Question: One issue in the U.S. statistical community in recent years is whether the American Statistical Association (ASA) should offer a certification process for its members so that statisticians meeting the qualifications could be designated as "Certified Statisticians." In 1994 the ASA surveyed its membership about this issue (data are in the file certify.dat). The survey was sent to all 18,609 members, and 5001 responses were obtained. Results from the survey were reported in the October 1994 issue of Amstat News. Assume that in 1994, the ASA membership had the following characteristics: Fifty-five percent have Ph.D.s and 38% have master's degrees; 29% work in industry, 34% work in academia, and 11 % work in government. The cross-classification between education and workplace was unavailable.

a. What are the response rates for the various subclasses of ASA membership? Are the nonrespondents MCAR? Do you think they are MAR?

b. Use raking to adjust the weights for the six cells defined by education (Ph.D. or non-Ph.D.) and workplace (industry, academia, or other). Start with an initial weight of 18,609/5001 for each respondent. What assumptions must you make to use raking? Estimate the proportion of ASA members who respond to each of categories 0 through 5 (variable certify), both with and without the raking weights. For this exercise, you may want to classify missing values in the "non-Ph.D." or the "other workplace" category.

c. Do you think that opponents of certification are justified in using results from this survey to claim that a majority of the ASA membership opposes certification? Why, or why not?