dspeyer comments on The Universal Medical Journal Article Error - Less Wrong

6 Post author: PhilGoetz 29 April 2014 05:57PM

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Comment author: dspeyer 06 April 2013 05:07:48AM 3 points [-]

If 11 out of 11 children studied have a property (no food coloring hyperactivity response), that's a bit stronger than "there exist 11 children with this property", though perhaps not quite "all children have this property".

Comment author: PhilGoetz 06 April 2013 01:30:59PM *  5 points [-]

That's not how it works. You measure the magnitude of an effect, then do a statistical test of the hypothesis that all of the children have a response, which gives a cutoff that the effect magnitude must reach to accept that hypothesis with 95% confidence. If only 10% of the children have such a response, you won't reach that cutoff. If 10% have a positive response and 10% have a negative response, you will detect nothing, no matter how big your sample is.