In Exercise 12 of Chapter 1 a study of characteristics of successful salespersons indicated that 44 of 120 sales managers rated reliability as the most important characteristic in salespersons. A study of a different industry showed that 60 of 150 sales managers rated reliability as the most important characteristic of a successful salesperson.
(a) At the 0.05 level of significance, do these opinions differ from one industry to the other?
(b) At these sample sizes, what is the power of this test, assuming a 30% importance rate in the first industry, and a 40% rate in the second? (Hint: At this sample size, you can assume the estimated standard error is very close to the true standard error.)
Exercise 12
A large hospital administers a “compassion burnout” survey to a random sample of nurses. The responses are scored on a scale of 0 = least burnout to 20 = most burnout. The responses of the nurses in the pediatric cancer and obstetrics units are summarized in Table 5.19. Use α = 5%.
(a) Is there evidence that typical scores differ in the two groups?
(b) Is there evidence that variability differs in the two groups?
(c) Why is the normality assumption of great importance in this situation?