The placebo effect.

The most important factors influencing the effects drugs and other therapeutic measures are discussed. i.e. 1) variations between different patients--"individual factors", 2) variations in the environment--"occupational factors", 3) variations in compliance, 4) variations in the spontaneous course of the disease, and 5) variations in the effect of placebo. It is pointed out that "the placebo effect" must always be allowed for when evaluating different methods of treatment.