I’m taking a break from end-of-semester madness to offer this mini-rant, inspired by a passage in this WP article, “Leading mathematician debunks value-added“:
When value-added models were first conceived, even their most ardent supporters cautioned about their use [Sanders 1995, abstract]. They were a new tool that allowed us to make sense of mountains of data, using mathematics in the same way it was used to understand the growth of crops or the effects of a drug. But that tool was based on a statistical model, and inferences about individual teachers might not be valid, either because of faulty assumptions or because of normal (and expected) variation.
Such cautions were qualified, however, and one can see the roots of the modern embrace of VAMs in two juxtaposed quotes from William Sanders, the father of the value-added movement, which appeared in an article in Teacher Magazine in the year 2000. The article’s author reiterates the familiar cautions about VAMs, yet in the next paragraph seems to forget them:
Sanders has always said that scores for individual teachers should not be released publicly. “That would be totally inappropriate,” he says. “This is about trying to improve our schools, not embarrassing teachers. If their scores were made available, it would create chaos because most parents would be trying to get their kids into the same classroom.”
Still, Sanders says, it’s critical that ineffective teachers be identified. “The evidence is overwhelming,” he says, “that if any child catches two very weak teachers in a row, unless there is a major intervention, that kid never recovers from it. And that’s something that as a society we can’t ignore” [Hill 2000].
(As you may be aware, a similar argument is sometimes made about charter schools, which were apparently intended to reform, and not replace, ordinary public schools).
So here’s the thing. I really don’t know what to make of value-added models, which have received alot of attention in the mainstream media ever since this hoopla in Los Angeles. I lack familiarity with statistics, and have read deeply conflicting accounts of their accuracy and meaningfulness in making education policy decisions both with regards to schools and individual teachers.
HOWEVER. Ask J. Robert Oppenheimer – just because you develop something doesn’t mean that you retain authority over its usage for all time, nor would that be desirable. What matters is how that technology can be used, and how it should be used, for independent moral, political, and practical reasons. Sanders, “the father of the value-added movement,” in the quote above makes substantive claims about how teachers ought to be treated, and about the ill effects of using VAMs in a particular way. But those are entirely separable from the statistical technique itself, and do not follow from it.
If value-added models, or charter schools, can in fact be used to improve education and, all other things considered, make sense to adopt, then to hell with their inventors’ intent. That is all.