Blind and Fair

When people expect to feel better, they sometimes do. A sugar pill can ease pain if the patient believes it is medicine. Doctors, too, can see what they hope to see. So a fair test tries to keep expectations from tilting the result.

That is the point of blinding. In a blind trial, patients do not know whether they received the real treatment or a placebo. In a double-blind trial, the people judging the results do not know either, so neither hope nor habit can leak in.

When you hear that a remedy worked, ask how it was tested. If everyone knew who got the treatment, good results may only show what people expected.

The two pills

A clinic tests a cream for a rash. Half the patients get the real cream and half get a plain one in an identical tube. Neither patients nor nurses know which is which until the end.

Both groups improve somewhat, and the real cream does only slightly better. Because nobody knew who got what, the small gap is a fairer measure of the cream itself.

Try this today Before trusting a claim that something worked, ask: did the people judging know who got what?