The Physicians' Health Study followed 22,000 male physicians for a period of several years. Approximately 11,000 took an aspirin every second day, while the rest took a placebo. At the completion of the study, it was noted whether a subject had experienced a heart attack during the period of the study. It was found that the aspirin group had significantly fewer heart attacks than the placebo group.
Which factor was used in this experiment?

Question

Quizplus · Accepted Answer

The factor used in this experiment was the medication used, specifically the comparison between aspirin and placebo. The study was designed to determine if taking aspirin every second day would lead to a lower incidence of heart attacks. The other factors listed, severity of the heart attack, use of a placebo, and length of study, were all variables that may have been measured or controlled for in the study, but they were not the primary factor being tested.

The Physicians' Health Study Followed 22,000 Male Physicians for a Period