6. To explore the efficacy of a combination of antihypertensive agents, 16 hypertensive patients were enrolled and randomly divided into a monotherapy regime group and a combination therapy regime group (eight patients in each group). Their systolic blood pressure (mmHg) before and after treatment was measured, as given in Table 8.8. The researcher first compared the baseline level of systolic blood pressure between the two groups using the two independent samples t-test. After failing to reject H0 (p=0.407), the researcher claimed that there was no statistical difference at baseline. Then, by conducting another independent t-test in comparing the posttreatment systolic blood pressures, the researcher concluded that there is no difference in efficacy between the monotherapy and combination therapy owing to an insignificant p value of 0.088.

Please answer the following questions:

(a) Is this analytical method appropriate? If not, please give reasons and use the appropriate method to compare the efficacy of the two therapeutic regimes.
What assumptions should be made when conducting this analysis?

(b) What is the 95% CI for the difference in efficacy between the monotherapy and combination therapy?