Pointer from Tyler Cowen. Some of the criticisms seem powerful to me, others less so. Basically, it possible to come up with disparate measures for the proportion of Jews in a segment of the population. Unz appears to have over-estimated the proportion of Jews admitted to elite colleges and under-estimated the proportion with high achievement (such as wins in the Putnam math exam). Note, however, that the people proposing revised estimates may be stretching things in order to prove their point.