Can You Repeat That?

One day you go for a checkup, and the doctor suggests something you should do to stay healthy.

- Alice Andre-Clark

Then, a few years later, the same doctor says not to follow that advice after all. Your doctor’s not indecisive. The work of careful researchers may lead scientists and health providers to say, “Yeah, never mind.”

Researchers sometimes try to re-create a past experiment, step by step, to see if they get the same results. It’s known as replication, and it’s something like members of a group double-checking each other’s work before they turn in a project to the teacher. One researcher conducts a study showing that a certain medicine—or scientific idea—works well. But before the scientific community accepts this result as fact, other researchers repeat the experiment. The results may be the same. (Awesome.) Or they may differ. (Hmm.)