gwern comments on Too good to be true - LessWrong

24 Post author: PhilGoetz 11 July 2014 08:16PM

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Comment author: gwern 21 July 2014 02:43:27PM 3 points [-]

Is there any reason at all to think that these medical studies didn't use 95%? The universal confidence level, used pretty much everywhere in medicine and psychology except in rare subfields like genomics, so universal that authors of papers typically don't even bother to specify or justify the confidence level?

Comment author: wedrifid 22 July 2014 02:32:09AM 2 points [-]

so universal that authors of papers typically don't even bother to specify or justify the confidence level?

I'd love to see a paper get published that justified the confidence level with "because if I wanted to do rigorous science I would have studied physics" or "because we only have enough jelly beans to run 30 studies, will only be given more jelly beans if we get a positive result and so need to be sure".

Comment author: private_messaging 21 July 2014 10:27:58PM *  2 points [-]

There's all sorts of things one has to control for, e.g. parent's age, that may inflate the error bars (if the error in imperfectly controlling for a co-founder is accounted for), putting zero within the error bars. Without looking at all the studies one can't really tell.

Some studies ought to also have a chance of making a superfluous finding that 'vaccines prevent autism', but apparently that was not observed either.

Comment author: gwern 22 July 2014 01:08:00AM 2 points [-]

There's all sorts of things one has to control for, e.g. parent's age, that may inflate the error bars (if the error in imperfectly controlling for a co-founder is accounted for), putting zero within the error bars. Without looking at all the studies one can't really tell.

What does that have to do with whether the researchers followed the nigh-universal practice of setting alpha to 0.05?

Comment author: private_messaging 22 July 2014 04:58:47AM *  2 points [-]

Example: I am measuring radioactivity with a Geiger counter. I have statistical error (with the 95% confidence interval), but I also have systematic error (e.g. the Geiger counter's sensitivity is 'guaranteed' to be within 5% of a specified value). If I am reporting an unusual finding, I'd want the result not to be explainable by the sum of statistical error and the bound on the systematic error. Bottom line is, generally there's no guarantee that "95% confidence" findings will go the other way 5% of the time. It is perfectly OK to do something that may inadvertently boost the confidence.

Comment author: mwengler 22 July 2014 03:16:18AM 1 point [-]

Suppose there were 60 studies that showed no correlation between autism and vaccines at a 99% confidence level. THen it would not be particularly surprising that there were indeed 60 studies with that result.

Would you expect the authors to point out that their result was actually 99% confident even though the usual standard, which they were not explicitly claiming anyway, was 95%?

Comment author: mwengler 22 July 2014 03:10:49AM *  0 points [-]

retracted