Question

There were ten patients who had trouble sleeping, and each patient tried several medications. Here we compare just the control (no medication) and drug. Does the drug offer an improvement in average sleep time? The Table 1 shows the sleep times, differences, and signed ranks.

Table 1: The Psychology Experiments at a Research Institution

Participant	1	2	3	4	5	6	7	8	9	10
Control	0.6	1.1	2.5	2.8	2.9	3.0	3.2	4.7	5.5	6.2
Drug	2.5	5.7	8.0	4.4	6.3	3.8	7.6	5.8	5.6	6.1
Difference	-1.9	-4.6	-5.5	-1.6	-3.4	-.8	-4.4	-1.1	-.1	.1
Signed rank	-6	-9	-10	-5	-7	-3	-8	-4	-1.5	1.5

A. Test a hypothesis with Wilcoxon signed-rank test at significance level .05. Hint: a one-tailed test.

B. Suppose that the assumption(s) is (are) satisfied to use the parried t test for the hypothesis test. We know that the sample mean difference (d bar) = -2.33 and s_d = 2.002 from the data. Conduct the parried t test, and state the conclusion with the statistical evidence.

Answer 1

ANS.

Wilcoxon Singed Rank Critical Value Table :-