On “Access to Teacher Quality” as the New Equity Concern

This from School Finance 101:

A short while back, the Center for American Progress posted their take-away from the Vergara decision. That takeaway was that equity of teacher quality distribution is the new major concern, or as they framed it Access to Effective Teaching. Certainly, the distribution of teaching quality is important. But let me set the record straight on a few major issues I have with this claim.

First, this is not new. It is relatively standard in the context of state constitutional litigation over equity and adequacy of educational resources to focus on the distributions of programs and services, as well as student outcomes, AND TEACHER ATTRIBUTES!

I (and many others) have regularly addressed these issues in reports and on the witness stand for years. It is important to understand that school finance equity litigation as it is often identified, actually tends these days to focus more broadly on equity and adequacy of educational programs and services, including teacher characteristics, and their relation to inequities and inadequacies of funding.

Second, modern measures of effective teaching, as I have explained in a previous post, are very problematic for evaluating “equity.” teacher effectiveness which have a tendency to be associated with demographic context and for that matter access to resources. To review, as I’ve explained numerous previous times, growth percentile and value added measures contain 3 basic types of variation:

1. Variation that might actually be linked to practices of the teacher in the classroom;
2. Variation that is caused by other factors not fully accounted for among the students, classroom setting, school and beyond;
3. Variation that is, well, complete freakin statistical noise (in many cases, generated by the persistent rescaling and stretching, cutting and compressing, then stretching again, changes in test scores over time which may be built on underlying shifts in 1 to 3 additional items answered right or wrong by 9 year olds filling in bubbles with #2 pencils).

Our interest in #1 above, but to the extent that there is predictable variation, which combines #1 and #2, we are generally unable to determine what share of the variation is #1 and what share is #2. A really important point here is that many if not most models I’ve seen actually adopted by states for evaluating teachers do a particularly poor job at parsing 1 & 2. This is partly due to the prevalence of growth percentile measures in state policy.

This issue becomes particularly thorny when we try to make assertions about the equitable distribution of teaching quality. Yes, as per the figure above, teachers do sort across schools and we have much reason to believe that they sort inequitably. We have reason to believe they sort inequitably with respect to student population characteristics. The problem is that those same student population characteristics in many cases also strongly influence teacher ratings.

As such, those teacher ratings themselves aren’t very useful for evaluating the equitable distribution of teaching. In fact, in most cases it’s a pretty darn useless exercise, ESPECIALLY with the measures commonly adopted across states to characterize teacher quality. Being able to determine the inequity of teacher quality sorting requires that we can separate #1 and #2 above. That we know the extent to which the uneven distribution of students affected the teacher rating versus the extent to which teachers with higher ratings sorted into more advantaged school settings.

Third and finally, claims of identifying some big new equity concern seem almost always intended to divert attention from the substantive persistent inequities of state school finance systems (like this). That is, the intent seems far too often to assert that equity can be fixed without any attention to funding inequity. That in fact, the inequity of teacher quality distribution is somehow exclusively a function of state statutory job protections for teachers and/or corrupt adult-self-interested district management and teachers union arrangements.

The assertion that state policy restrictions (and no other possible major cause?) on local contractual agreements is the primary (or even a significant) cause of teaching inequity is problematic at many levels.

First, variation in access to teacher quality across schools within districts varies… across districts. Some districts (in California or elsewhere) achieve reasonably equitable distributions of teachers while others do not. If state laws were the cause, these effects would be more uniform across districts – since they all have to deal with the same state statutory constraints (perhaps those district leaders testifying at trial in Vergara and bemoaning the inequities within their own districts were, in fact, revealing their own incompetence,rather than the supposed shackles of state laws?).*

Second and most importantly, teacher quality measures and attributes tend to vary far more across than within districts, making it really hard to assert that district contractual constraints (which constrain within, not cross-district sorting) imposed by state law have any connection to the largest share of teacher quality inequity...