Avoiding Human Error
People sometimes feel better — and some even perform better on medical tests — if they think a treatment is helping them. And doctors sometimes convince themselves that a certain treatment is helping a patient because the physician really wants the patient to get better.
Clinical trials are designed to screen out these normal, unscientific human biases, which can skew results of scientific tests. That is why they follow these procedures:
Most Phase II and Phase III clinical trials are randomized studies, in which participants are randomly assigned to one treatment or another.
Most trials are placebo-controlled. Participants are selected at random, usually by computer, to receive the experimental treatment or a placebo that looks and tastes like a drug but has no effect.
Clinical trials are blind or double-blind. In blind studies, subjects don't know which treatment they receive. In double-blind studies, neither the subjects nor the study staff know which patients are taking a drug and which are getting the placebo.
