Question

determine whether the study is an experiment or an observational study, and then identify a major problem with the study. the physicians health study involved 22,071 male physicians. based on random selections, 11,037 of them were treated with aspirin and the other 11,034 were given placebos. the study was stopped early because it became clear that aspirin reduced the risk of myocardial infarctions by a substantial amount. this is an experiment because the researchers apply a treatment to the individuals. what is a major problem with the study? a. the results apply only to individuals with heart disease. b. the results apply only to male physicians. c. there is no blinding or replication, which has a high chance of leading to bias. d. this is a convenience sample with voluntary response, which has a high chance of leading to bias.

Explanation:

The study is an experiment as researchers apply treatments (aspirin and placebo). The major problem is that the sample consists only of male physicians, so the results may not be generalizable to other populations. Option A is wrong as the study didn't focus only on those with heart - disease. Option C is incorrect as the study doesn't lack replication (it has a large sample divided into two groups) and blinding could be present but isn't mentioned as an issue. Option D is wrong as it's not a convenience sample with voluntary response.

Answer:

B. The results apply only to male physicians