I don’t care about the original intent of value-added models

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.


  • Chapman, L.H wrote:

    As a philopspohy major you seem to think that the end justifies the means. You seem to think it is OK whack teachers with a statistical methodology imported into education from genetic engineering, with all sorts of assumptions that do not apply to the world of teaching and learning but are, in fact, distorted to make the statistical model work. You also seem to be oblivious to the fact that this model equates Effective Teaching with higher than average mean estimated test score gains on tests. That is the defacto meaning of improving education being marketed by policy wonks. Please fo not become part of the problem of thinking that anything goes if it improves education, especially in a historic movement when “improvement” is almost exclusively tied to scores on standardized tests in a few subjects with content that is selected because it is machine scorable.

  • Jimdilly wrote:

    VAM are just a smokescreen for an ideological attack on (a) public schooling, and indirectly on (b) federal governance. The intent, for the most part, disqualifies it from rational and moral use.

    The results that you appear to applaud, are hardly worth applauding. VAM make the fundamental mistake that all present attempts at measuring school and teaching quality make: they assume that test scores accurately reflect learning and that learning is a direct product of teaching. We know all of this to be, if not false, then at least spurious.

    First, tests are simply not adequate as a sole measure of learning and teaching quality. Education involves so many other things—-and you as a philosopher of education should have at least read your way to that conclusion if not convinced yourself of it–that to attempt to compress it down to one sometimes reliable measurement is to ask the blind man who only touches the elephant’s trunk to tell you what an elephant is.

    If we are to pretend that test scores can tell us everything we need to know (and absurd proposition, but I will play along), then we do know that teaching is responsible the most important SCHOOL effects on test scores, but school effects pale in comparison to NON-SCHOOL effects such as socioeconomic status and all the other stuff we know. Do you really want to ‘reform’ education based on data that (a) is inferentially suspect at best, and (b) represents only a narrow band of the totality of the thing being reformed? Such actions can only make the thing targeted WORSE, not better.

    In short, VAM is for those who merely want to destroy what exists in order to implement…well, nothing. If VAM is used to take out what is there, then it must be used to create the replacement, and VAm can only do what it does—test. It cannot teach. You cannot build a curriculum on it. Eventually you will have to bring in everything else you previously discarded and the only thing that will be different is the funding mechanisms and access, which, again, is the main intent of the charter school, tuition-voucher, privatization crowd.

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