Thursday, September 27, 2007

"Way whiter than average" 

Long-time friend of this blog Linda Seebach is blogging herself now, and in this post tells us why the claims that Minnesota is doing so well on standardized tests are missing the point.
Every two years, the NAEP tests a national sample of fourth- and eighth-graders in reading and mathematics (see for details). White and Asian students score significantly higher on this and similar tests, and so do more affluent students. The reasons are hotly debated, as are the potential solutions, but that is a different debate.

Results are reported as scaled scores on a single yardstick, so that, for instance, the average score for fourth grade reading is 220 and for eighth grade reading 261 (math, 239 and 280, respectively).

Scaled scores for black and Hispanic students are 25 to 30 points lower than for white students, depending on the test. Those are big differences, the equivalent of two to three grades � the visible sign of the achievement gap you hear so much about.

NAEP�s charts show states as green if they�re above average, yellow if they are not statistically different from average, and red if they are below average. Overall, Minnesota is refreshingly green on all four tests.

But look at black students separately, and Minnesota is dull yellow average on all four tests. Likewise, it is average for Hispanic students on all four tests. For white students, it is above average statistically on three of the four, but by only a few points. The state owes its high ranking primarily to the fact that it draws a larger proportion of its students from groups that on average score higher.
Income probably matters as well as family size. Linda correctly gets the idea of ceteris paribus; NAEP report cards, not so much.