Each healing encounter, and every treatment, has specific and non-specific treatment effects. Non – specific effects, or placebo effects, are the benefits felt by the patients because of the nature of the healing encounter. Although difficult to quantify and control, a number of authors recognize that the non-specific component of management has an additive effect on the overall clinical outcome. It has been reported that due to the physical interaction and social nature of chiropractic, there is a strong non-specific component in the management process, but to what extent it facilitates in the healing encounter is unknown. It has also been shown that spinal manipulation has a clinical effect which exceeds that of placebo; therefore it is possible for its effect to be muted or amplified, depending on the presence or absence of non-specific effects. For the above reasons this study was conducted in an attempt to map the size of the non-specific effect in the healing encounter by manipulating the practice setting in which the patients were treated.
