Judge in NY State Throws Out ‘Value-Added Model’ Ratings

I am pleased that in an important, precedent-setting case, a judge in New York State has ruled that using Value-Added measurements to judge the effectiveness of teachers is ‘arbitrary’ and ‘capricious’.

The case involved teacher Sheri Lederman, and was argued by her husband.

“New York Supreme Court Judge Roger McDonough said in his decision that he could not rule beyond the individual case of fourth-grade teacher Sheri G. Lederman because regulations around the evaluation system have been changed, but he said she had proved that the controversial method that King developed and administered in New York had provided her with an unfair evaluation. It is thought to be the first time a judge has made such a decision in a teacher evaluation case.”

In case you were unaware of it, VAM is a statistical black box used to predict how a hypothetical student is supposed to score on a Big Standardized Test one year based on the scores of every other student that year and in previous years. Any deviation (up or down) of that score is attributed to the teacher.

Gary Rubinstein and I have looked into how stable those VAM scores are in New York City, where we had actual scores to work with (leaked by the NYTimes and other newspapers). We found that they were inconsistent and unstable in the extreme! When you graph one year’s score versus next year’s score, we found that there was essentially no correlation at all, meaning that a teacher who is assigned the exact same grade level, in the same school, with very similar  students, can score high one year, low the next, and middling the third, or any combination of those. Very, very few teachers got scores that were consistent from year to year. Even teachers who taught two or more grade levels of the same subject (say, 7th and 8th grade math) had no consistency from one subject to the next. See my blog  (not all on NY City) herehere, here,  here, herehere, here, here,  herehere, and here. See Gary R’s six part series on his blog here, here, here, here, here, and here. As well as a less technical explanation here.

Mercedes Schneider has done similar research on teachers’ VAM scores in Louisiana and came up with the same sorts of results that Rubinstein and I did.

Which led all three of us to conclude that the entire VAM machinery was invalid.

And which is why the case of Ms. Lederman is so important. Similar cases have been filed in numerous states, but this is apparently the first one where a judgement has been reached.

(Also read this. and this.)

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