balanced placebo design
balanced placebo designA trial design in which participants are recruited for a study where either an active drug or a placebo will be administered. Half of the participants are told they are receiving the active drug and half are told they are receiving the placebo—but in both groups, only half of the participants therein actually receive the drug or placebo as told, i.e., half are intentionally misinformed about which arm they are in. This permits independent and combined assessment of drug and placebo effects.
The balanced placebo design is useful because it provides a direct assessment of the drug effect, independent of expectancy. It has most commonly been deployed to test the role of expectancy on the effects of alcohol and caffeine consumption, usually with healthy volunteers. It has the advantage that the “told receiving drug”/“received drug” non-deceptive arm has more external validity than the double-blind administration in conventional randomised trials, because they more accurately represent what happens in clinical practice.