1). 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. 2). Using the RestaurantTips data set which compares servers, tips, and credit card usage, we have the following two-way table. It shows the servers and whether or not the customer used a credit card to pay for their meal. (Hint: You'll have to total each column and row to calculate the proportions below) a) Compute and interpret a 95% confidence interval for the proportion of bills paid with a credit card. (Statkey: Confidence Interval for Proportion) b) Compute and interpret 90% confidence intervals for the proportion of bills for each server. (Statkey: Confidence Interval for Proportion) c) From the confidence intervals in part b) does it appear that Server B is responsible for 1/3 of the bills this week?
1). 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
2). Using the RestaurantTips data set which compares servers, tips, and credit card usage, we have the following two-way table. It shows the servers and whether or not the customer used a credit card to pay for their meal. (Hint: You'll have to total each column and row to calculate the proportions below)
a) Compute and interpret a 95% confidence interval for the proportion of bills paid with a credit card. (Statkey: Confidence Interval for Proportion)
b) Compute and interpret 90% confidence intervals for the proportion of bills for each server. (Statkey: Confidence Interval for Proportion)
c) From the confidence intervals in part b) does it appear that Server B is responsible for 1/3 of the bills this week?
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