[somenameforme]

The placebo effect controls for all of these factors, and is entirely real. It's the reason placebo control groups exist in the first place. If the placebo effect was just statistical noise, then you could greatly simplify trials by just taking a random group of people as the control, and do away entirely with trying to hide from both patient and technician who is taking the drug - because it wouldn't matter at all.

You can see the opposite effect with the less well known nocebos [1]. People can experience objectively measurable side effects (such as bloating) that are in no way associated with a treatment, but that a patient believes to be a side effect. It can even be fatal. The article references aboriginals who will 'curse' one another resulting in the victim rapidly dying, because he believes so strongly that he is going to die! A similar thing in contemporary medicine has been observed with those who receive a fatal prognosis of cancer with them ending up dying long before there is any way the cancer could have killed them.

[1] - https://en.wikipedia.org/wiki/Nocebo