> and that happens when everyone is measured in a similar way (or randomized to different ways) But that's exactly the issue -- that the similarity or randomne

> and that happens when everyone is measured in a similar way (or randomized to different ways) But that's exactly the issue -- that the similarity or randomness is one way for one study, and another way for another study, because of culturally different sets of nurses and/or patients. In other words, you're right it's not affecting results within a study, but it makes comparison between studies questionable. And it makes it equally questionable whether a study's results apply to you, if your signal is 10 units off of a study's signal, and occurs across a cutoff that determines whether you should take a medication or not.