Danger of assumptions

“A study shows!”

If a single intervention comparison study shows that people who got one kind of therapy did better or worse than people who got something else, it does not mean that is the final answer.

The same interventions are often compared in more than one study. Those different studies can have very different results. This can happen because the comparisons were more fair or less fair in the different studies, or because they were small studies with few people or events.

BEWARE if a claim about intervention effects is based on a single study.

REMEMBER: Think about whether there are other studies that compare the same intervention and a systematic review of all the relevant studies.