Dr Manocha discusses the placebo effect in this excerpt from his thesis.
The word “placebo” has been in use for at least the last 2 centuries, if not longer. While detailed discussion of the placebo effect is not possible here, suffice to say that at least part of the phenomenon appears to relate to an interaction between the subjective mind and the physical body leading to a biologically measurable outcome. Generally speaking, a clinician researcher’s rule of thumb is that one third of a control group taking placebo might manifest improvements. However the placebo response in clinical trials can be much higher (for instance Maclennan (2001) demonstrates that the placebo effect in hormone replacement therapy trials can be as high as 50%). Indeed it has been suggested that “harnessing the power of the placebo” ought to be a major priority for researchers looking for new strategies to alleviate illness.