Remember that study by Ron Unz about how Harvard was discriminating in favor of Jews? Andrew Gelman at Columbia has reviewed the numbers, and claims on his website that Unz seriously mangled his math.
In his article, Unz claims to have found that elite college admissions underrepresent Asian-Americans (in comparison to their academic talent achievements) and overrepresent Jews, leaving non-Jewish whites squeezed out. Looking at the statistics more carefully, we see no evidence that Jews are admitted preferentially compared to other whites. Unz’s error arose because he used different sorts of information with different biases that did not cancel out but actually reinforced each other, underestimating the proportion of high-achieving Jews and overestimating the Jewish presence among Ivy League students.
I have long argued that meritocracy can’t work (for more recent discussion, see here and here) and so I’m sympathetic to Unz’s general concerns. But it looks like he garbled the analysis for one of his main points.
The statistical message: your conclusion is only as good as the numbers that go into it.