EXTRA CREDIT PROBLEM. For research I'm doing, I'd like to explain the differences across U.S. states in the fraction of K-12 students classified as "gifted and talented".
I assume initially that in large groups of students, the fraction who are gifted and talented should be about the same. I say "about" because external conditions--poverty, for one--may prevent some students from reaching their potentials and also because high IQ workers are probably unequally distributed across states and so, therefore, would their children.
I further assume that most of the variation seen in the table linked to above is therefore due to differences in how "gifted and talented" students are identified which depends, in turn, on the educational systems of the states. Some support for this is that the simple correlation between the fraction of adults who hold graduate or professional degrees and the percentage of gifted and talented students is -.08; the fraction of adults who have bachelor's degrees, -.06; and median household income, -.03.
Some potential causal factors I want to explore are teacher unionization; political attitudes; economic and social inequality; and availability of private schools (which in the long run also would need to be explained).
As a quick-and-dirty test of the first two factors, I computed the correlation with the fraction of the electorate voting for Bush in 2004. I get .135; .195 without Maryland.