Do workers on diff erent shift s get diff erent amounts of sleep per week? Some people believe that shift workers who regularly work the night shift (12.00 a.m. to 8.00 a.m.) or aft ernoon shift (4.00 p.m. to 12.00 a.m.) are unable to get the same amount of sleep as day workers because of family schedules, noise, amount of daylight, and other factors. To test this theory, a researcher samples workers from day, aft ernoon, and night shift s and asks each worker to keep a sleep journal for one week. Th e following data represent the number of hours of sleep per week per worker for the diff erent shift s. Use the Kruskal–Wallis test to determine whether there is a signifi cant diff erence in the number of hours of sleep per week for workers on these shift s. Use 0.05.

Day Shift Afternoon Shift Night Shift 52 45 41 57 48 46 53 44 39 56 51 49 55 48 42 50 54 35 51 49 52 43