Tyler Cowen points us to a terrific post on educational outcomes across states by Dave Burge, also known as Iowahawk:
[T]he lion’s share of state-to-state variance in test scores is accounted for by differences in ethnic composition. Minority students – regardless of state residence – tend to score lower than white students on standardized test, and the higher the proportion of minority students in a state the lower its overall test scores tend to be.
Please note: this has nothing to do with innate ability or aptitude. Quite to the contrary, I believe the test gap between minority students and white students can be attributed to differences in socioeconomic status. And poverty. And yes, racism. And yes, family structure. Whatever combination of reasons, the gap exists, and it’s mathematical sophistry to compare the combined average test scores in a state like Wisconsin (4% black, 4% Hispanic) with a state like Texas (12% black, 30% Hispanic).
So how to compare educational achievement between two states with such dissimilar populations? In data analysis this is usually done by treating ethnicity as a “covariate.” A very simple way to do this is by comparing educational achievement between states within the same ethnic group. In other words, do black students perform better in Wisconsin than Texas? Do Hispanic students perform better in Wisconsin or Texas? White students? If Wisconsin’s kids consistently beat their Texas counterparts, after controlling for ethnicity, then there’s a strong case that maybe Texas schools ought to become a union shop.
Suffice it to say, that’s not quite the case:
To recap: white students in Texas perform better than white students in Wisconsin, black students in Texas perform better than black students in Wisconsin, Hispanic students in Texas perform better than Hispanic students in Wisconsin. In 18 separate ethnicity-controlled comparisons, the only one where Wisconsin students performed better than their peers in Texas was 4th grade science for Hispanic students (statistically insignificant), and this was reversed by 8th grade. Further, Texas students exceeded the national average for their ethnic cohort in all 18 comparisons; Wisconsinites were below the national average in 8, above average in 8.
Perhaps the most striking thing in these numbers is the within-state gap between white and minority students. Not only did white Texas students outperform white Wisconsin students, the gap between white students and minority students in Texas was much less than the gap between white and minority students in Wisconsin. In other words, students are better off in Texas schools than in Wisconsin schools –especially minority students.
I should stress that there are many — an infinite number, really — confounding variables. Texas is poorer, it is burdened by a troubled history of enslavement and segregation, and much else. Of course, many of these factors suggest that Wisconsin should be outperforming Texas.