The takeaway on VAM from Bruce Baker: journos need help going beneath shallow "error rate" critiques of released data; VAM may only be slightly more predictive in student math standardized test scores as linked to teachers than ELA (which is to say still, hardly at all); and even so, the largest data set contains 18,000 data points, some of whom may be teachers counted twice. By contrast there are 150,000 teachers in NYC. So the data that has been released may only apply to 10% of the teaching workforce in NYC.
You’ve Been VAM-IFIED! Thoughts (& Graphs) on the NYC Teacher Data
In fact, as I’ve pointed out before on this blog, it is quite likely that value added estimates that retain bias by failing to fully control for outside influences are actually likely to be more stable over time (to the extent that the outside influences remain more stable over time). And that’s not…