Faulty logic

“A study shows!”

If one treatment comparison (study) shows that people who got one treatment did better or worse than people who got something else, it does not mean that is the final answer.

The same treatments are often compared more than once by different researchers. 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 treatment effects is based on a single study.

REMEMBER: Ask if there are other studies that compare the same treatments and a careful summary of all the relevant studies.