Question

Aspirin prevents blood from clotting and so helps prevent strokes. The Second European Stroke Prevention Study asked whether adding another anticlotting drug named dipyridamole would be more effective for patients who had already had a stroke. Here are the data on strokes collected during the two years of the study: Stroke No Stroke Total Aspirin alone 203 1446 1649 Aspirin + dipyridamole 156 1494 1650 Is there a significant difference in the proportion of strokes for the two groups? (a) The hypotheses to be tested are H9: 11 = 12 versus Ha: 21*12 Ho: M1 = H2 versus Ha: M1 * M2 Ho: P1 = P2 versus Ha: P1 P2 • Ho: P1 = P2 versus Ha: P1 P2 (b) What is the ... ... test statistic? ... p-value? X (Use 2 decimal places) (Use 4 decimal places) X

Explain and answer question B please!

Answer 1

(b) Excel add-in (Mega Stat) procedure: Step 1: In EXCEL, Select Add-Ins Mega Stat Hypothesis Tests. Step 2: Choose Proportion vs. Hypothesized Value. Step 3: Choose Data Input Step 4: In Group 1, enter the value 203 underx and enter the value 1649 undern Step 5: In Group 2, enter the value 156 underx and enter the value 1650 under n Step 6: Enter 0 Under Hypothesized difference. Step 7: Choose not equal in alternative. Step 8: Click OK Excel add-in (Mega Stat) output:

Hypothesis test for two independent proportions p2 p1 Pc 0.1088 p (as decimal) 0.1231 0.0945 203/1649 156/1650 359/3299 p (as fraction) 156 203. 359. X 1649 1650 3299 n 0.0286 difference 0. hypothesized difference 0.0108 std. error 2.63 z 0084 p-value (two-tailed) Test statistic: z 2.63 p-value: 0.0084