A local bank has three branch offices. The bank has a liberal sick leave policy and a vicepresident was concerned about employees taking advantage of the policy. She thought that the tendency to take advantage depended on the branch at which the employee worked. To see whether there were differences in the time employees took for sick leave, she asked each branch manager to sample employees randomly and record the number of days of sick leave taken during 1990. Ten employees were chosen, and the data are listed Below. Branch 1 Branch 2 Branch 3
15 11 18
20 15 19
19 11 23
14

a. Do the data indicate a difference in branches? Use a level of significance of 0.05.
b. Use Duncan’s multiple-range test to determine which branches differ. Explain your results with a summary plot.