The Hawthorne effect.
D002641:Chicago; D015987:Effect Modifier, Epidemiologic; D017598:Efficiency, Organizational / Q000266:history*; D005260:Female; D049673:History, 20th Century; D006801:Humans; D007221:Industry / Q000266:history*; D008029:Lighting / Q000266:history; D016272:Occupational Health / Q000266:history*