In Exercise 5.62, we see that students who study by giving themselves quizzes recall a greater proportion of words than students who study by reading. In Exercise 5.62 we see that there is an effect, but often the question of interest is not ‘‘Is there an effect?” but instead ‘‘How big is the effect?” To address this second question, use the information in Exercise 5.62 to find and interpret a 99% confidence interval for the difference in proportions p_Q − p_R, where p_Q represents the proportion of items correctly recalled by all students who study using a self-quiz method and p_R represents the proportion of items correctly recalled by all students who study using a reading-only approach. Assume that the standard error for a bootstrap distribution of such differences is also about 0.07.  

Exercise 5.62

Cognitive science consistently shows that one of the most effective studying tools is to self-test. A recent study reinforced this finding. In the study, 118 college students studied 48 pairs of Swahili and English words. All students had an initial study time and then three blocks of practice time. During the practice time, half the students studied the words by reading them side by side, while the other half gave themselves quizzes in which they were shown one word and had to recall its partner. Students were randomly assigned to the two groups, and total practice time was the same for both groups. On the final test one week later, the proportion of items correctly recalled was 15% for the reading-study group and 42% for the self-quiz group. The standard error for the difference in proportions is about 0.07. Test whether giving self-quizzes is more effective and show all details of the test. The sample size is large enough to use the normal distribution.