Green jelly beans and subsamples

Excited about that new randomized controlled trial result showing  microcredit works for men between the ages of 30 and 40.5 who have between 3 and 4 siblings? Or how about yet another study showing a positive effect of aid on growth when you restrict it to countries with good governance and names that begin with the letters A to F? XKCD hits the nail on the head as to why you should approach these results with extreme caution:

2 thoughts on “Green jelly beans and subsamples

  1. Nicolas

    April 6, 2011 at 11:38am

    Matt (or others), do you know any references off the top of your head to papers that show if/how you can adjust standard errors when dealing with things like this (e.g. when you’re estimating over different subsamples)?

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