When regressions go wrong...or too right
Via the excellent Simoleon Sense weekly roundup , I find this link which claims to discover "the single most important question in your life". The research behind it claims to have found that the answers on a single kindergarten test can predict future income, college attendance, quality of college, college graduation (and while they're at it, a close link between college ranking and future wages). I don't have the knowledge to challenge their results and I would not want to suggest that there's anything untoward about this research. But one thing makes me really, really puzzled: the results are too good . Specifically, the regressions show an incredibly close linear fit between rank (or percentile) in the kindergarten test, and absolute salary. And a similarly close fit between rank in the test, and percentage chance of going to college. The following image not only shows that unrealistically close linear fit, but they also imply an almost constant d...