ASVAB, Income Inequality, and Libraries

Following up on a hunch from a comment, I dug out a state-by-state ranking on income inequality from PBS's NOW documentary program (based on data going back to 2008). The income inequality rankings look at the income gap between rich and poor, the gap between the middle class and the rich, and differential rates of income growth. For example, New York state had the worst income inequality in the nation with the most wealthy 20% of families making 8.7 times as much as the poorest 20% of families. New York also had the greatest growth in disparity over a ten year period.

As one might expect, there was a substantial negative correlation between income disparity and pass rates on the ASVAB (r=-.54). States with the least well-prepared youth (in terms of achievement n the ASVAB) also generally had the worst income disparities.

But here's the very interesting thing: The public libraries connection discussed in the previous post was almost completely independent of this issue. A regression analysis pitting income inequality and library visits against each other as predictors of ASVAB showed that both had powerful effects in the same analysis. In other words, whatever is going on with the connection of income disparity to ASVAB pass rates, it is independent of the mechanism that causes a relation between public library visits and ASVAB.

So what is going on here? It is easy to speculate that in states with great income inequality there is probably also a substantial disparity in the quality of public education between poor school districts and well-off districts, so the connection to preparedness (again remembering that the ASVAB tests basic literacy and numeracy skills) is not unexpected there. But apparently the urge to visit the library or the availability of opportunities to do so is still an independent animal. Still open to ideas here... Anybody? Will go fetch the data if someone can think of another variable to put into the mix...