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Components of placebo effect: randomised controlled trial in patients with irritable bowel syndrome. T. J. Kaptchuk, J. M. Kelley, L. A. Conboy, R. B. Davis, C. E. Kerr, E. E. Jacobson, I. Kirsch, R. N. Schyner, B. H. Nam, L. T. Nguyen, M. Park, A. L. Rivers, C. McManus, E. Kokkotou, D. A. Drossman, P. Goldman, A. J. Lembo. Bmj 2008: 336(7651); 999-1003. [Medline] [Abstract] [Full text] [PDF]. Description: The authors suggest that the placebo affect can be separated into three components: the process of observation itself (the Hawthorne effect), the therapeutic ritual associated with a placebo, and the patient-practitioner interactions. They then test this empirically in a three arm single blind study. There were significant differences between the arms of the study, and the effect of the patient-practitioner interactions was the strongest effect. Added 2008-11-17 to Category: Placebos in research.