4. To investigate the plasma renin activity in cirrhosis patients with different degrees of ascites, patients were randomly selected. Their plasma renin activity (g/ml) was measured. The results are given in Table 12.11.

Please answer the following questions:

(a) Is the data appropriate to conduct ANOVA here? If not, choose an appropriate method and state H0 and H1 .

(b) Please test whether there is any difference in the plasma renin activity level between the four groups?

(c) What is the conclusion if the global test rejects H0 ? Which method can be used if we need to further infer which two groups have different distributions?
Conduct the test and interpret the results.