Scientific studies, and news coverage about them, often declare that a study “controlled” for certain variables.
For example, the Washington Post reported on a study of GLP-1 drugs and a hormonal disorder. The article noted that “women on GLP-1s lost more weight than those in control groups.”
A couple months earlier, the Post reported on a different study about GLP-1s and bone and tendon injuries. It said “researchers controlled for age, sex, race and tobacco use” and found that people taking GLP-1s had higher risk of skeletal disorders than nonusers.
This language typically gives the impression that having a control enhances credibility. But what exactly does “control” mean? And should you be impressed by it?
I’ve been a statistician for many years, and my recent research has shown that 90% of American adults would base decisions on statistics, at least sometimes, if they understood the basic concepts better. Control is one such concept.
Understanding controls can help you assess how well a study’s conclusions are supported by evidence, and can help you judge the media’s interpretation of new research.
