There's a new piece about IQ, income, and SAT scores in the WSJ. The DI Friday post had linked to a story about it with a somewhat misleading quote about IQ and pure luck. I decided to investigate.

Originally Posted by WSJ piece by Charles Murray
Why should almost all of the income effect be concentrated in the first hundred thousand dollars or so? The money itself may help, but another plausible explanation is that the parents making, say, $60,000 are likely to be regularly employed, with all the things that regular employment says about a family. The parents are likely to be conveying advantages other than IQ such as self-discipline, determination and resilience—“grit,” as this cluster of hard-to-measure qualities is starting to be called in the technical literature.

Families with an income of, say, $15,000 are much more likely to be irregularly employed or subsisting on welfare, with negative implications for that same bundle of attributes. Somewhere near $100,000 the marginal increments in grit associated with greater income taper off, and further increases in income make little difference.