Mitch Pearlstein looks at a Catholic school to support the case of vouchers.

A common myth is that schools across the country with lots of low-income students are less-well-funded than schools with fewer low-income students. The opposite, actually, is more routinely the case. Minnesota, in fact, recently ranked fifth best in the nation in terms of "extra poverty-based funding per student living below the poverty line." This (benevolent) gap was $3,075.

But given that African-Americans in Minneapolis are doing unusually poorly academically, how do these conflicting findings compute?

To complicate matters even more, consider Ascension School, a K-8 Catholic school in north Minneapolis. Students are overwhelmingly minority; they're overwhelmingly non-Catholic; and in 2005, 90 percent of eighth-graders there passed Minnesota's Basic Skills test in math and 95 percent passed Minnesota's Basic Skills test in reading.

In contrast, eighth-graders in Minneapolis public schools, in 2003, passed at these rates in math: 82 percent for whites; 57 percent for Asian/ Pacific Islanders; 41 percent for Hispanics; 40 percent for American Indians; and 28 percent for blacks. ... MPS scores were significantly better in reading than they were in math; but again, they were significantly below Ascension's reading scores.

What are tuition rates (for non-parishioners) in inner-city Catholic schools in the state? According to the Minnesota Catholic Conference, they average under $3,200 for elementary schools and under $8,000 for high schools. By contrast, as long ago as 2003 -- in the wake of a recession -- federal, state, and local revenues in Minneapolis Public Schools totaled $13,658 per "pupil unit."

As I often teach, costs are always costs to someone. So when you hear that parents of the students at Ascension are the cream skimmed off the top, what does that mean? It probably means that those parents contribute more of the cost of their children's education in time and sweat than in cash dollars. (It's also worth noting that a religious school subsidizes education in order to gain the ears of children they hope to convince to be lifelong followers of the religion ... and adults who fill the coffers.)

So I'm not as comfortable with the dollars-for-dollars comparison Mitch is making here. But it raises another point. Let's suppose parents invest in their children's education (for whatever reasons) by a combination of time, talent and money. If there are no financing constraints, parents choose for their children the school that makes the best use of the parents' time and talent, given the cost of borrowing for education. Constraints on financing educational choice, not least of which come from taxation to pay for public education, lead some families who can benefit to public rather than private choices. Vouchers are a way of overcoming the financing constraint; this is why vouchers seem particularly attractive to African-American families who both may face financing constraints and have historically cared a great deal about the educaiton of their children (and thus willing to commit lots of time and talent.)