Something else that could make the placebo effect seem real: Only publishing positive results. There seems to be this unspoken agreement that once the efficacy

Something else that could make the placebo effect seem real: Only publishing positive results. There seems to be this unspoken agreement that once the efficacy of a treatment is shown in scientific studies there is no placebo "factor" contributing to it helping people. But of course after a successful study the placebo effect of that treatment is stronger, because it convinces even more people (doctors, sceptics) that it's effective. Consider umpteen variants of the same treatment being tested, and one of them showing strong results (https://www.xkcd.com/882/ https://www.xkcd.com/882/). That medicine then surfs on its own placebo effect until its efficacy is refuted (if that ever happens) by another study or it's replaced by something with a stronger result.