Werther et al. (A -26) examined the -leucocyte count in 51 subjects with colorectal cancer and 19 healthy controls. The cancer patients were also classified into Dukes’s classification (A, B, C) for colorectal cancer that gives doctors a guide to the risk, following surgery, of the cancer coming back or spreading to other parts of the body. An additional category (D) identified patients with disease that had not been completely resected. The results are displayed in the following table.

Perform an analysis of these data in which you identify the sources of variability and specify the degrees of freedom for each. Do these data provide sufficient evidence to indicate that, on the average, leucocyte counts differ among the five categories? Let and find the p value. Use Tukey’s procedure to test for significant differences between individual pairs of sample means.