The Wrong Way To Publish Teacher Prep Value-Added Scores

As discussed in a prior post, the research on applying value-added to teacher prep programs is pretty much still in its infancy. Even just a couple of years of would go a long way toward at least partially addressing the many open questions in this area (including, by the way, the evidence suggesting that differences between programs may not be meaningfully large).

Nevertheless, a few states have decided to plow ahead and begin publishing value-added estimates for their teacher preparation programs. Tennessee, which seems to enjoy being first -- their Race to the Top program is, a little ridiculously, called “First to the Top” -- was ahead of the pack. They have once again published ratings for the few dozen teacher preparation programs that operate within the state. As mentioned in my post, if states are going to do this (and, as I said, my personal opinion is that it would be best to wait), it is absolutely essential that the data be presented along with thorough explanations of how to interpret and use them.

Tennessee fails to meet this standard. 

Selection Versus Program Effects In Teacher Prep Value-Added

There is currently a push to evaluate teacher preparation programs based in part on the value-added of their graduates. Predictably, this is a highly controversial issue, and the research supporting it is, to be charitable, still underdeveloped. At present, the evidence suggests that the differences in effectiveness between teachers trained by different prep programs may not be particularly large (see here, here, and here), though there may be exceptions (see this paper).

In the meantime, there’s an interesting little conflict underlying the debate about measuring preparation programs’ effectiveness, one that’s worth pointing out. For the purposes of this discussion, let’s put aside the very important issue of whether the models are able to account fully for where teaching candidates end up working (i.e., bias in the estimates based on school assignments/preferences), as well as (valid) concerns about judging teachers and preparation programs based solely on testing outcomes. All that aside, any assessment of preparation programs using the test-based effectiveness of their graduates is picking up on two separate factors: How well they prepare their candidates; and who applies to their programs in the first place.

In other words, programs that attract and enroll highly talented candidates might look good even if they don’t do a particularly good job preparing teachers for their eventual assignments. But does that really matter?

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