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Brain_Hawk t1_jduukr7 wrote

Part that's missing in the above answer is that the original research was usually blinded. Typically a third person who is not involved in data collection or analysis is the one who was aware of the group labels.

To do properly, during the initial statistical analysis to groups are also done blinded. For example you label them groups a, b, c. Only after you have performed statistical analysis of the effects of the intervention, for example, then do you afterwards get to unblind

So it can happen you have what looks like a very nice effect, and then realize that it's the placebo group we got better! I've seen it happen :p


wargarbleEleventyTen t1_jduvobv wrote

Oh definitely. I could have been clearer in the comment. The person(s) doing the assignment are not involved in either the data collection nor the analysis.

Everyone else does not know, what branch a subject is in, until the study is over. If something serious happens you can of course unblind immediately.