Some things you just have to keep saying over and over until it sinks in. Some very elementary facts about education statistics have not yet sunk in with Arne Duncan, who is … what is he? … oh yes: the U.S. Secretary of Education!

“Far too few of their high school graduates are actually prepared to go on to college,” Duncan said on Bloomberg Television’s “Political Capital With Al Hunt” airing tonight and tomorrow. “I feel very, very badly for the children there.”

So let’s limp up to explain it once more.

The canard about Texas school failure came up back in February when the innumerate and statistically incompetent New York Times columnist Paul Krugman tried to argue that low levels of public spending in Texas resulted in poor educational outcomes.

Compassion aside, you have to wonder — and many business people in Texas do — how the state can prosper in the long run with a future work force blighted by childhood poverty, poor health and lack of education.

This was shortly after the brouhaha over public-sector unions — which mostly means teacher unions — in Wisconsin. The Economist chimed in with a snide comparison:

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 whole Krugman/Economist thesis was decisively exploded by blogger Iowahawk in a March 2nd post. Iowahawk pointed out what everyone acquainted with psychometric or educational statistics knows: that the only meaningful population comparisons are those that have been disaggregated by race and ethnicity.

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 tests, and the higher the proportion of minority students in a state the lower its overall test scores tend to be … 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).

Iowahawk went on to perform the necessary disaggregation, showing that:

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.

Iowahawk got a huge email bag from that post. He responded with a follow-up on March 5th, from which:

After controlling for ethnicity, compared to the running-dog Gang of Five non-collective bargaining states (TX, VA, SC, NC, GA), Wisconsin is a (1) middling performer for white students; (2) below middling for Hispanic students, and (3) an absolute disaster for black students.

If I were Rick Perry I’d have Iowahawk’s analysis displayed on billboards on state highways. It’s depressing, though not the least bit surprising, that Barack Obama’s secretary of education has never heard of it, nor even (it seems) given a moment’s thought to the underlying issues.