Please pardon this brief departure from my normal folderol, but every so often a member of the chattering class issues a nugget of stupidity so egregious that no amount of mockery will suffice. Particularly when the issuer of said stupidity holds a Nobel Prize.

Case in point: Paul Krugman. The Times' staff economics blowhard recently typed, re the state of education in Texas:

And in low-tax, low-spending Texas, the kids are not all right. The high school graduation rate, at just 61.3 percent, puts Texas 43rd out of 50 in state rankings. Nationally, the state ranks fifth in child poverty; it leads in the percentage of children without health insurance. And only 78 percent of Texas children are in excellent or very good health, significantly below the national average.

Similarly, The Economist passes on what appears to be the cut-'n'-paste lefty factoid du jour:

Only 5 states do not have collective bargaining for educators and have deemed it illegal. Those states and their ranking on ACT/SAT scores are as follows: South Carolina – 50th

North Carolina – 49th

Georgia – 48th

Texas – 47th

Virginia – 44th If you are wondering, Wisconsin, with its collective bargaining for teachers, is ranked 2nd in the country.

The point being, I suppose, is that unionized teachers stand as a thin chalk-stained line keeping Wisconsin from descending into the dystopian non-union educational hellscape of Texas. Interesting, if it wasn't complete bullshit.

As a son of Iowa, I'm no stranger to bragging about my home state's ranking on various standardized test. Like Wisconsin we Iowans usually rank near the top of the heap on average ACT/SAT scores. We are usually joined there by Minnesota, Nebraska, and the various Dakotas; Vermont, Maine, New Hampshire...

... beginning to see a pattern? Perhaps because a state's "average ACT/SAT" is, for all intents and purposes, a proxy for the percent of white people who live there. In fact, the 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.

Luckily, there is data to answer this question via the National Assessment of Educational Progress (NAEP). The NAEP is an annual standardized test given to 4th and 8th graders around the country to measure proficiency in math, science, and reading. Participation is fairly universal; if you've had a 4th or 8th grader in the last few years, you're probably familiar with it. Results are compiled on the NAEP website, broken down by grade, state, subject and ethnicity.

So how does brokeass, dumbass, redneck Texas stack up against progressive unionized Wisconsin?

2009 4th Grade Math

White students: Texas 254, Wisconsin 250 (national average 248)

Black students: Texas 231, Wisconsin 217 (national 222)

Hispanic students: Texas 233, Wisconsin 228 (national 227)

2009 8th Grade Math

White students: Texas 301, Wisconsin 294 (national 294)

Black students: Texas 272, Wisconsin 254 (national 260)

Hispanic students: Texas 277, Wisconsin 268 (national 260)

2009 4th Grade Reading

White students: Texas 232, Wisconsin 227 (national 229)

Black students: Texas 213, Wisconsin 192 (national 204)

Hispanic students: Texas 210, Wisconsin 202 (national 204)

2009 8th Grade Reading

White students: Texas 273, Wisconsin 271 (national 271)

Black students: Texas 249, Wisconsin 238 (national 245)

Hispanic students: Texas 251, Wisconsin 250 (national 248)

2009 4th Grade Science

White students: Texas 168, Wisconsin 164 (national 162)

Black students: Texas 139, Wisconsin 121 (national 127)

Hispanic students: Wisconsin 138, Texas 136 (national 130)

2009 8th Grade Science

White students: Texas 167, Wisconsin 165 (national 161)

Black students: Texas 133, Wisconsin 120 (national 125)

Hispanic students: Texas 141, Wisconsin 134 (national 131)

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.

Conclusion: instead of chanting slogans in Madison, maybe it's time for Wisconsin teachers to take refresher lessons from their non-union counterparts in the Lone Star State.

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Update: a few emails complaining that I focused on NAEP 4th and 8th graders, and didn't address Krugman's "point" about Texas dropout rates. I would note that "average state dropout rate" (non-controlled for ethnicity) is as uninformative as "average state ACT/SAT." Some research suggests Hispanic students, for example, tend to have higher dropout rates than black students despite performing marginally better on standardized tests. But still, the level of Texas dropout rate claimed by Krugman (38%+) is rather disturbing, and it does seem rather odd that somewhere between 8th and 12th grade Texas students are attacked by an epidemic of stupidity.

So I decided to investigate.

Mr. Krugman (please note - I don't call anyone "Doctor" unless they can write me a prescription for drugs) doesn't mention where he gets his dropout statistic from. I suspect a database somewhere in his lower intestine. So I endeavored to find most detailed / recent / comprehensive state-by-state dropout table, which appears to be this 2006-7 report from the National Center for Education Statistics.

Event Dropout Rates for 9th-12th graders during 2006-7 school year:

White students: Texas 1.9%, Wisconsin 1.2% (national average 3.0%)

Black students: Texas 5.8%, Wisconsin 7.8% (national 6.8%)

Hispanic students: Texas 5.6%, Wisconsin 5.2% (national 6.5%)

White and Hispanic Texas students indeed seem to dropout at a higher rate than their counterparts in Wisconsin, although in both cases (a) the difference is not statistically significant; and (b) in both cases, both states are significantly below the national average. Among black high school students, Texans have significantly lower dropout rates than their national cohort and Wisconsinites. Black high school students in Wisconsin have significantly higher dropout rates than national.

Your first question is probably, "why do the union teachers in Wisconsin hate black students?" Sorry, can't help you there, I'm stumped too.

Your second question is probably, "why are these number so discrepant with the 30% dropout numbers I've always read?" The reason is these are event rates, representing the probability a kid will drop out in a specific year. For cumulative dropout rate, you would have to compound; for example if the 1-year dropout rate is 10% the 4 year survival would roughly be 0.9^4 =~ 65%.