This blog used to be ALL ABOUT education policy, and then I became a teacher and stopped having the energy to follow it. But I really need to respond to what's going on in NYC with the teacher-level test score analysis.
First of all, we knew this was the direction they were heading a while back when they started assigning individual ID numbers to each student, the kind that can be used for value-added assessment. However, in order for that to work, the students need to be taking the type of test that was designed for value-added assessment, such as the TerraNova. The New York State tests, to my knowledge at least, were not designed for value-added assessment. They weren't even really designed to show gains from one year to the next for each individual student, though that's what the city would like to do with the data.
I'm not opposed to analyzing and publicizing "value-added" data, given the appropriate measuring tool. But I think whatever experiment they're cooking up right now could not possibly provide meaningful insight into whether this is a system that can work in NYC. It's like using a teaspoon to judge a 100-meter dash.