The scores for both tests are on a 500 point scale, with a designed standard deviation of 50. In the proceeding table, these are are converted to IQ estimates with a mean of 97.5, corresponding to the national average NAEP scores of 281.67 for math and 262.29 for reading, and a standard deviation of 15. The math and reading scores are given equal weighting.
I'm operating under the presumption that the average IQ in the US is 98. The reason the IQ estimates are based on a national mean of 97.5 is to take into account private schools, whose students on average score 15 points higher on the math test and 19 points higher on the reading test, corresponding to an estimated 5.1 IQ advantage over their public school counterparts. Representing a little more than one-tenth of the school age population, this yields a national average of 98. The estimates assume that the private school advantage relative to public schools is equal across states. That is, the public school score, plus 5.1 multiplied by the percentage of a state's students enrolled in private schools, gives the state's overall estimated average IQ.
Again in the spirit of the 2004 IQ hoax, states are colored in accordance to how their populations voted in the 2008 Presidential election. Light red (blue) indicates the margin of victory for McCain (Obama) was less than 10%; dark red (blue) indicates it was 10% or more:
|51.||District of Columbia||91.2|
* "Department of Defense Education Activity", comprised of the children of service members serving outside of the US. Despite a demographic pool (58.1% white, 22.0% black, 9.9% Hispanic, 9.0% Asian/Pacific Islander, 1.0% Native American) that suggests the DoDEA should be found near the bottom of the rankings, if measured as though an independent state, DoDEA schools place 11th, between Maryland and Wisconsin. Military men aren't morons.
An aunt of mine who lives in Alabama has joked that the state's motto is "thank God for Mississippi". The demographic transition the nation is undergoing, however, has already made her remark a bit antiquated. I suspect in a few years' time, both Alabama and Mississippi will be able to thank him for the Southwest.
Although I have substituted reading scores for science scores in converting NAEP scores into IQ estimates four years down the road, the 2005 and 2009 state level results still correlate with one another at a very vigorous .91 (p=0). There is a great deal of consistency in the average state scores among different cohorts of test takers, suggesting that deriving IQ estimates from NAEP testing is sound.
As has historically been the case, the further north one goes, the smarter the population becomes. During the 2008 election cycle, Half Sigma frequently decried the perceived abandonment of the GOP by the cognitive upper crust of the voting population. Indeed, the best-performing red states are only tenuously so. Middling Kansas tops the list of solidly Republican states. I suspect, however, given the staggering growth in government spending that is coming down the pike over the next four years, that 2010 will reveal a reversal in that trend to be occuring.