In Teacher Ratings, Good Test Scores Are Sometimes Not Good Enough

This from the New York Times:

At Public School 234 in TriBeCa, where children routinely alight for school from luxury cars, roughly one-third of the teachers’ ratings were above average, one-third average and one-third below average. 

At Public School 87 on the Upper West Side, where waiting lists for kindergarten spots stretch to stomach-turning lengths, just over half the ratings were above average. The other half were average or below average on measure, based on student test scores. 

And at Public School 29 in Cobble Hill, Brooklyn, where many young parents move to send their children, four of the teachers’ ratings were above average, seven were average and five were below. 

The New York City Education Department on Friday released the ratings of some 18,000 teachers in elementary and middle schools based on how much they helped their students succeed on standardized tests. The ratings have high margins of error, are now nearly two years out of date and are based on tests that the state has acknowledged became too predictable and easy to pass over time...

In one extreme case, the formula assigned an eighth-grade math teacher at the prestigious Anderson School on the Upper West Side the lowest possible rating, a zero, even though her students posted test scores 1.22 standard deviations above the mean — normally good enough to rank in the 89th percentile. Her problem? The formula expected her high-achieving students to be 1.84 standard deviations higher than the average — roughly the 97th percentile.