High-pressure sales tactics or door-to-door salespeople can be quite offensive. Many people succumb to such tactics, sign a purchase agreement, and later regret their actions. In the mid-1970s, the Federal Trade Commission implemented regulations clarifying and extending the rights of purchasers to cancel such agreements. The accompanying data is a subset of that given in the article “Evaluating the FTC Cooling-Off Rule” (J. of Consumer Affairs, 1977: 101–106). Individual observations are cancellation rates for each of nine salespeople during each of 4 years. Use an appropriate test at level .05 to see whether true average cancellation rate depends on the year.

Salesperson 1 2345 67 89 1973 2.8 5.9 3.3 4.4 1.7 3.8 6.6 3.1 0.0 1974 3.6 1.7 5.1 2.2 2.1 4.1 4.7 2.7 1.3 1975 1.4 .9 1.1 3.2 .8 1.5 2.8 1.4 .5 1976 2.0 2.2 .9 1.1 .5 1.2 1.4 3.5 1.2