Agreed, which was why I included: "...while some of the conditions may be real for some people". I'm not disputing real conditions like your wife's, I'm saying some medical conditions these days have symptoms so loosely interpretable by the general public that anyone with achy legs may think they have it, and thus possibly try to medicate it. Perhaps this leads to a greater number of these people in study groups.... and perhaps that leads a measurable rise in placebo effectiveness. Anyhow, just an idle theory.