The tendency for subjects in a study to respond to almost any change as an indicator of appreciation that someone has taken the trouble to alter conditions.
The effect (often beneficial, almost always present) which an encounter with a provider, health program or other part of the health system has on a patient which is independent of the medical content of the encounter. The Hawthorne effect is similar to the placebo effect. but is not obtained intentionally and is the effect of the encounter with a provider or program on the patient rather than of what they do for him. The effect may be changed (intentionally or not) by changing the provider or program (for instance by painting a clinic or changing its appointments system). Since health services research usually changes the services being studied simply by being done or in unintentional ways, the resulting change in the Hawthorne effect may well confound the results of the research. The name comes from classic industrial management experiments at the Hawthorne plant of the Western Electric Company.