Jersey Jazzman: Random Thoughts On Using VAM for Teacher Evaluation

Jersey Jazzman: Random Thoughts On Using VAM for Teacher Evaluation:

Random Thoughts On Using VAM for Teacher Evaluation

You may have read the piece in the New York Times today by Kevin Carey on the passing of William Sanders, the father of idea of using value-added modeling (VAM) to evaluate teachers. Let me first offer my condolences to his family.

I'm going to skip a point-by-point critique of Carey's piece and, instead, offer a few random thoughts about the many problems with using VAMs in the classroom:

1) VAM models are highly complex and well beyond the understanding of almost all stakeholders, including teachers. Here's a typical VAM model:

Anyone who states with absolute certainty that VAM is a valid and reliable method of teacher evaluation, yet cannot tell you exactly what is happening in this model, is full of it.

There was a bit of a debate last year about whether it matters that student growth percentiles (SGPs) -- which are not the same as VAMs, but are close cousins -- are mathematically and conceptually complex. SGP proponents make the argument that understanding teacher evaluation models are like understanding pi: while the calculation may be complex, the underlying concept is simple. It is, therefore, fine to use SGPs/VAMs to evaluate teachers, even if they don't understand how they got their scores.

This argument strikes me as far too facile. Pi is a constant: it represents something (the circumference of a circle divided by its diameter) that is concrete and easy to understand. It isn’t expressed as a conditional distribution; it just is. It isn’t subject to variation depending Jersey Jazzman: Random Thoughts On Using VAM for Teacher Evaluation:

Big Education Ape: Individual-Level VAM Scores Over Time: “Less Reliable than Flipping a Coin” | VAMboozled! - http://bigeducationape.blogspot.com/2015/08/individual-level-vam-scores-over-time.html