Teacher Quality

The War On Error

The debate on the use of value-added models (VAM) in teacher evaluations has reached an impasse of sorts. Opponents of VAM use contend that the imprecision is too high for the measures to be used in evaluation; supporters argue that current systems are inadequate, that all measures entail error but this doesn’t preclude using the estimates. 

This back-and-forth may be missing the mark, and it is not particularly useful in the states and districts that are already moving ahead. The more salient issue, in my view, is less about the amount of error than about how it is dealt with when the estimates are used (along with other measures) in evaluation systems.

Teachers certainly understand that some level of imprecision is inherent in any evaluation method—indeed, many will tell you about colleagues who shouldn’t be in the classroom, but receive good evaluation ratings from principals year after year. Proponents of VAM often point to this tendency of current evaluation systems to give “false positive” ratings as a reason to push forward quickly. But moving so carelessly that we disregard the error in current VAM estimates—and possible methods to reduce its negative impacts—is no different than ignoring false positives in existing systems.

Attention To Pay

The debate over how best to restructure teacher salary systems is older than I am—with good reason: Instructional salaries represent roughly 40 percent of current K-12 public school expenditures.  And some of the arguments for changing current salary structures make sense, at least in theory. 

For instance, there is a case for tying step increases (typically awarded according to years of service) to additional measures, such as strengthened evaluation systems and curriculum-linked professional development (as is the case in the recently-ratified Baltimore contract). These types of changes, if they are bargained and approved by teachers, could be of real benefit to all stakeholders.

At the same time, it’s unfortunate that some of the talking points used commonly by those who wish to overhaul teacher salary systems are rather misleading and oversimplified. Not only do they sometimes seem designed to inspire outrage against teachers, they also tend to obscure or ignore important facts about the relationship between teacher pay and teacher quality.  Three such arguments seem particularly pervasive.

The Teaching Experience

** Also posted here on “Valerie Strauss’ Answer Sheet” in the Washington Post.

The topic of teacher experience is getting a lot of attention in education debates.  In part, this makes sense, since experience (years of service) does play several important roles in education policy, including teachers’ raises and transfer/layoff policies. 

Usually, experience is discussed in terms of its relationship to performance –whether more experienced teachers produce larger student test score gains than less experienced teachers.  There is a pretty impressive body of research on this topic, the findings of which are sometimes used to argue for policy changes that eliminate the role of experience in salary and other employment policies.  Proponents of these changes often argue that experience is only weakly related to performance, and therefore shouldn’t be used in determining salary and other conditions of work.  It is not unusual to hear people say that experience doesn’t matter at all.

As is often the case when empirical research finds its way into policy debates, the “weakly related” characterization of the findings on the experience/achievement relationship borders on oversimplification, while the claim that experience doesn’t matter is flat-out wrong.  The relationship is substantial but context-dependent, and blanket statements about it often hide as much as they reveal.

How Deep Is The Teacher Bench?

On most sports teams, coaches assess players in part by considering who is available to replace them. Teams with “deep benches” have more leeway in making personnel changes, because quality replacements are available.

The same goes for teaching. Those who aggressively wish to start firing larger numbers of teachers every year rely on an obvious but critical assumption (often unstated): that schools and districts can find better replacements.

In other words, it is both counterproductive (and very expensive) to fire teachers if you can’t replace them with a more effective alternative. Even those few commentators who have addressed this matter sometimes ignore another important fact: The teacher labor market is about to change dramatically, with a massive wave of retirements lasting 5-10 years. Thus, most current assumptions about the stability and quality of the applicant pool over this period may be unsupportable.

The numbers are a bit staggering.