This initial analysis of the NYC data was surprising to me in some ways:

Over all, however, the teacher data reports tended to be highly correlated to the schools' grades. Last year, 79 percent of high-performing math teachers worked in "A" or "B" schools, according to the Education Department. But there was no relationship between a school's demographics and its number of high- or low-performing teachers: 26 percent of math teachers serving the poorest of students had high scores, as did 27 percent of teachers of the wealthiest.

Across the years covered by the reports, teachers at the top and bottom of the performance scale tended to stay there. Officials said 521 teachers were rated in the bottom 5 percent for at least two of the five years, while 696 were repeatedly in the top 5 percent. And 68 percent of math teachers in the top or the bottom quarter of the rankings in 2009-10 were in the same category in their multiyear scores.

Parents tend to focus on a school's rating, but the data showed variation in a building. At P.S. 230 in Kensington, Brooklyn, seven fourth-grade English teachers ranged from the 12th to the 99th percentile.

Hundreds of the highest-rated teachers taught students considered to be difficult to educate, like those not proficient in English or with special needs — perhaps because the model predicted those students would perform poorly.

At P.S. 49, in the Mott Haven section of the Bronx, state test scores for the students in a certain fifth-grade math teacher's class should have been in the 13th percentile citywide, based on their demographics and past performance on the exams. Yet under the teacher's guidance, the students ended up scoring close to the city average. The teacher, in turn, was rated "high."

I would have expected schools serving higher percentages of poor and minority students to have a greater concentration of below-average teachers (which is what numerous other studies show). Re. the last two paragraphs, perhaps the model's adjustments for students' disadvantages OVER-compensates???

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