Do unionized teachers do a better job of teaching?

As the thuggish demonstrations by members of public-employees unions continue in Wisconsin, a number of stories in the media have compared education performance in that state--with unionized teachers--to the performance in states like Texas (non-unionized).

On ACT/SAT scores, for example, Wisconsin ranks 2nd while Texas ranks 47th.

So OH WOW, unionized teachers must be much better, right?

Blogger Iowahawk was skeptical. He noted that Texas has a far higher percentage of black and Hispanic students (12% and 30%) than Wisconsin (4% each), and it's no secret that those groups have lower average scores than whites and Asians. He also noted that there's no evidence that this is due to differences in ability but could easily be due to the effect of lower family income and higher percentage of single-parent households--long known to affect educational results.

Was it possible that Texas' lower ranking on ACT/SATs was caused simply by its higher percentage of minority students?

He also noted that there was a nationwide standardized test--the National Assessment of Educational Progress (NAEP)--that published results broken down by race. And it told a very interesting tale:

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.

Let me note again that the above results don't suggest that whites are smarter: I suspect that if one were to control for family income and percentage of two-parent families, there would be no statistically significant difference in the scores of the 3 groups. But the NAEP results clearly show that when scores are compared between identical groups, Texas wins in 17 of the 18 areas tested.

Conclusion: Media articles alleging better performance by unionized teachers are simply propaganda.