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Kevin comments on Study shows existence of psychic powers. - Less Wrong Discussion

3 Post author: bentarm 12 November 2010 01:46AM

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Comment author: Kevin 12 November 2010 06:24:21AM 5 points [-]

what sort of p-values would you need to see in that paper in order to believe with, say, 50% probability that the effect measured is real?

P-values won't do it. Psi experiments consistently have high sounding significance because the trials are so large. Mass replication is what will make me believe.

Comment author: SeventhNadir 12 November 2010 10:12:35AM *  2 points [-]

That critique doesn't really work for t-tests though does it? Sure, as n increases so does your chance that the finding is statistically significant, but it also reduces the chance of the data being a fluke. If you flip a fair coin a million times holding a banana in your left hand and it comes up heads 55% of the time... there's some explaining to do. Even if the explanation is that it wasn't a fair coin.

Comment author: CarlShulman 12 November 2010 07:06:09PM *  3 points [-]

Failures to set up or follow proper experimental procedures (giving hints, not fully random presentation, etc) or otherwise introducing a slight biasing effect will show an effect which is puny. With low n, this won't be statistically significant, but with high n it will appear very statistically significant.

Comment author: SeventhNadir 12 November 2010 07:41:48PM *  0 points [-]

That's true, statistical significance isn't the most sophisticated statistic. My rule of thumb is looking at the p and d values.