Question

(23.20) Subjects with preexisting cardiovascular symptoms who were receiving subitramine, an appetite suppressant, were found to be at increased risk of cardiovascular events while taking the drug. The study included 9802 overweight or obese subjects with preexisting cardiovascular disease and/ or type 2 diabetes. The subjects were randomly assigned to subitramine (4897 subjects) or a placebo (4905 subjects) in a double-blind fashion. The primary outcome measured was the occurrence of any of the following events: nonfatal myocardial infarction or stroke, resuscitation after cardiac arrest, or cardiovascular death. The primary outcome was observed in 546 subjects in the subitramine group and 470 subjects in the placebo group.

Do the data give good reason to think that there is a difference between the proportions of treatment and placebo subjects who experienced the primary outcome?

State hypotheses, find the test statistic and the P-value.

Test statistic (±±0.001) z = ____

P-value (±±0.001) = _____

Answer 1

Given that,

For Subitramine group : n1 = 4897, x1 = 546 and

For Placebo group : n2 = 4905, x2 = 470 and

Pooled proportion is,

The null and alternative hypotheses are,

H0 : p1 = p2

Ha : p1 ≠ p2

Test statistic is,

=> Z = 2.546

p-value = 2 * P(Z > 2.546) = 2 * 0.0054 = 0.0108

=> p-value = 0.0108