The Art of Statistical Scamming in Experiments

John Bohannon writes,

Here’s a dirty little science secret: If you measure a large number of things about a small number of people, you are almost guaranteed to get a “statistically significant” result. Our study included 18 different measurements—weight, cholesterol, sodium, blood protein levels, sleep quality, well-being, etc.—from 15 people. (One subject was dropped.) That study design is a recipe for false positives.

Usually, I think of health studies as bad because they are non-experimental. But this is a way to scam experimental studies.

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2 Responses to The Art of Statistical Scamming in Experiments

  1. Bryan Willman says:

    See also Slate Star Codex commentary on same:
    http://slatestarcodex.com/2015/05/30/that-chocolate-study

  2. 3rdMoment says:

    Even with a large sample you still have the multiple comparisons problem. No matter how many subjects you have, you’ll still get a false positive about 5% of the time.

    What small sample does is exacerbate the statistical significance filter…the false positives you do get will look like really big effects.

    http://andrewgelman.com/2011/09/10/the-statistical-significance-filter/

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