Question: What stratification variable(s) would you use for each of the following situations?
a A political poll to estimate the percentage of registered voters in Arizona who approve of the job the governor is doing
b A telephone survey of students at your university, to estimate the total amount of money students spend on textbooks
c A sample of high schools in New York City, to estimate what percentage of high schools offer one or more classes in computer programming
d A sample of public libraries in California, to study the availability of computer resources and the per capita expenditures
e A survey of anglers visiting a freshwater lake, to learn about which species of fish are preferred
f An aerial survey to estimate the number of walrus in the pack ice near Alaska between 1730 east and 154° west longitude
g A sample of prime-time (7-10 P.M., Monday through Saturday; 6-10 P.M., Sunday) TV programs on CBS, to estimate the average number of promotional announcements (ads for other programming on the station) per hour of broadcast