Reformers like Cerf, Klein, Weisberg, and even Secretary Duncan often use the term “value-added scores” to refer to how they would quantify the teacher evaluation process. It is a phrase that sends chills down the spine of most teachers’-union officials. If, say, a student started the school year rated in the fortieth percentile in reading and the fiftieth percentile in math, and ended the year in the sixtieth percentile in both, then the teacher has “added value” that can be reduced to a number. “You take that, along with observation reports and other measures, and you really can rate a teacher,” Weisberg says.
Steven Brill, The Rubber Room, in the New Yorker.
A student. Well, no, Mr Weisberg, you really can't.
One can't help feeling that Mr Weisberg, Mr Brill and the New Yorker would all benefit from the services of a statistician. (Not that they actually need someone like AG for this kind of thing, but it would be infra dig, presumably, to call on someone who had merely mastered the material in an introductory course for undergraduates.)