GFBrandenberg does the math and finds that NY's "value-added measures" of teachers have near-zero predictive ability of effectiveness. It's lying with statistics. He encourages everyone to delve into the same data file and check his results.
Now I Understand Why Bill Gates Didn’t Want The Value-Added Data Made Public
In plain English, what that means is that there is essentially no such thing as a teacher who is consistently wonderful (or awful) on this extremely complicated measurement scheme. How teacher X does one year in “value-added” in no way allows anybody to predict how teacher X will do the next year. T…