Product testing. A company is producing and marketing new reading activities for elementary school children that it believes will improve reading comprehension scores. A researcher randomly assigns third graders to an eight-week program in which some will use these activities and others will experience traditional teaching methods.

At the end of the experiment, both groups take a reading comprehension exam. Their scores are shown in the backto-

back stem-and-leaf display.

a) Do these results suggest that the new activities are better? Test an appropriate hypothesis with a Wilcoxon (or Mann-Whitney) rank-sum test and state your conclusion.

b) How would you re-design this study? What nonparametric method would be appropriate then?