To Blind or Not to Blind
A word about blinded studies.
When possible, medical researchers like to blind, or mask, their clinical trials. In a single-blinded trial, participants do not know whether they are in the intervention group or the control group until the trial ends. In a double-blinded trial, neither investigators nor participants know which group a participant is assigned to until the trial's conclusion.
Blinding is another way of reducing bias that may distort a study's results. For example, investigators may behave differently toward participants whom they know are receiving the experimental intervention.
However, blinding is not always feasible. In a trial comparing surgery with chemotherapy, for example, blinding would be impossible -- both doctors and participants would know which intervention was being applied.
Cancer prevention clinical trials are sometimes blinded, but cancer treatment trials rarely are.
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