Doug, It seems that there are numbers galore in the neo stoddardian treatise on the rising tide of low IQ immigrants by George (once Jorge) Borjas. It seemed to me that Bhagati rang his bell pretty hard in his review and exchange with Borjas in the WSJ Sept or Oct of last year. But it won't make much difference. Will have to understand the ideology that sustains the view.
Now Borjas' argument fits in with Cox's. Immigrants are disproportionately of lower inherent quality as evidenced by IQ tests. This explains why they are concentrating at the bottom of the income distribution the curve of which they are widening to the left.
So the income curve is becoming skewed instead of remaining Gaussian or unimodal in appearance. If we realize that the wierdness comes from the superimposition of two normal distributions--that the population (aside from blacks and a few asians) is increasingly a mixture of two groups with distinct racial origins: caucasians and indios mexicanos--then we can understand why the increasingly skewed income distribution curve really can serve as a racially classificatory argument.
This then follows up on the move that Adolphe Bertillon and then Karl Pearson made in their demographic analyses as brilliantly discussed by Alain Desrosieres, The Politics of Large Numbers: A History of Statistical REasoning (harvard, 1999).
I think this eugenicist subtext is what Carrol and Angela have rightly feared may be implicit in Cox's and surely Borjas' discourse.
Yours, Rakesh