The Hawthorne Effect

In the 1920s, researchers went to the Hawthorne Works factory. They wanted to see if better lighting improved productivity.

They increased the lights. Productivity went up. They decreased the lights. Productivity went up. They returned the lights to normal. Productivity went up.

Why?

Because the workers knew they were being watched. They worked harder because the scientists were there.

The Observer Effect

This is the Hawthorne Effect. The act of observing a phenomenon changes the phenomenon.

In clinical trials, this is a nightmare.

Patients in a trial take their medicine more regularly. They eat better. They exercise. They want to please the doctors.

This makes the drug look better than it is. In the real world, patients are messy. They forget pills. They eat junk.

The White Coat Hypertension

A classic example is blood pressure.

When a doctor measures your blood pressure, it goes up. You are nervous.

If you measure it at home, it is lower.

If a study only uses the doctor's measurements, it will overestimate the problem.

The Diagnosis

Science tries to be an invisible observer. But it is impossible.

When you read a study, remember: these are not normal people. These are people on a stage.