So there is evidence that for study participants who do not drop out, the placebo arm improves on average. That doesn't mean that a placebo helps patients. It could as easily be a measure of selective attrition: participants who feel worse on average may be far more likely to leave a study, and that will leave participants who are better…
So there is evidence that for study participants who do not drop out, the placebo arm improves on average. That doesn't mean that a placebo helps patients. It could as easily be a measure of selective attrition: participants who feel worse on average may be far more likely to leave a study, and that will leave participants who are better on various measures, on average, than the study population at the beginning, AND that they were less likely to feel worse as the study proceeded. Miracle: placebo medicine helps! Or not.
So there is evidence that for study participants who do not drop out, the placebo arm improves on average. That doesn't mean that a placebo helps patients. It could as easily be a measure of selective attrition: participants who feel worse on average may be far more likely to leave a study, and that will leave participants who are better on various measures, on average, than the study population at the beginning, AND that they were less likely to feel worse as the study proceeded. Miracle: placebo medicine helps! Or not.