Viewing a single comment thread. View all comments

[deleted] t1_jdunkeg wrote

[deleted]

18

wargarbleEleventyTen t1_jduu65e wrote

That goes a bit far, though it may happen with some specific experiment is psychology.

Otherwise double blind means that neither the person getting the treatment nor the people administering it and collecting data know, if the subject is part of the treatment or the control arm.

Generally everyone knows what the study is about. Bit hard to keep that secret, really.

11

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

6

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.

3

rootofallworlds t1_jduxppr wrote

This doesn't seem right, not in all cases anyway.

In most clinical trials the patient knows that it's a clinical trial, what condition is being treated, and that they will be randomly given either the treatment or a placebo. It would be unethical for the participants to not know that.

You seem to be thinking of psychology studies, where it is commonplace to tell subjects and workers a study is about one thing when really it's about another.

6

ZZ9ZA t1_jdykcq0 wrote

It’s not always a placebo, either. It’s my understanding that in testing of things like pain killers the control is often something like a benzodiazepine just because the patient understands that they are likely to feel relaxed/sleepy and a true placebo would essentially unblind the study.

2

YesWeHaveNoTomatoes t1_jdv5lis wrote

>A blind study has a researcher doing something with a subject that is not aware of the study's true / detailled aim.
>
>A double blind study has a researcher tasking another researcher to do something with a subject, with neither the subject nor the tasked researcher knowing what the study is actually about.

This is not correct and would violate principles of informed consent. A blind study is one in which the participant doesn't know if they are getting the the study drug (or procedure or whatever) or if they're getting a placebo. A double-blind study is one in which the participant and the tasked researcher both don't know whether the participant is getting the drug or the placebo. In all cases the participant must know what the purpose of the drug is and any negative effects taking it or not taking it may have.

5