Question: What test of differences is appropriate in each of the following situations?

(a) Average campaign contributions of Democrats, Republicans, and Independents are to be compared.

(b) Managers and supervisors have responded “yes,” “no,” or “not sure” to an attitude question. Their answers are to be compared.

(c) One-half of a sample receives an incentive in a mail survey. The other half does not.

(d) Stockbrokers in the East, Midwest, and West were asked their annual incomes. Regional comparisons are to be made. A comparison of response rates is desired.