A Case For Value-Added In Low-Stakes Contexts

Most of the controversy surrounding value-added and other test-based models of teacher productivity centers on the high-stakes use of these estimates. This is unfortunate – no matter what you think about these methods in the high-stakes context, they have a great deal of potential to improve instruction.

When supporters of value-added and other growth models talk about low-stakes applications, they tend to assert that the data will inspire and motivate teachers who are completely unaware that they’re not raising test scores. In other words, confronted with the value-added evidence that their performance is subpar (at least as far as tests are an indication), teachers will rethink their approach. I don’t find this very compelling. Value-added data will not help teachers – even those who believe in its utility – unless they know why their students’ performance appears to be comparatively low. It’s rather like telling a baseball player they’re not getting hits, or telling a chef that the food is bad – it’s not constructive.

Granted, a big problem is that value-added models are not actually designed to tell us why teachers get different results – i.e., whether certain instructional practices are associated with better student performance. But the data can be made useful in this context; the key is to present the information to teachers in the right way, and rely on their expertise to use it effectively.

For example, one of the most promising approaches for translating less-than-informative teacher effect estimates into actionable information is disaggregation – i.e., presenting the estimates by student subgroup. For instance, if a teacher is told that her English language learners tend to make less rapid progress than her native speakers, this is potentially useful – she might rethink how she approaches those students and what additional supports they may need from the school system. Similarly, if there are strong gains among those students who started out at a lower level (i.e., their score the previous year) and stagnation for those starting out at a higher level, this suggests the need for more effective differentiation.

Needless to say, such information still requires strong professional judgment. In the end, teachers and administrators will have to figure out the specifics of any plan for improvement. In addition, since subgroups (e.g., non-native English speakers) are smaller samples, most teachers would need to have a few years of data in order to discern these patterns. Finally, and most obviously, teachers who do not understand or trust the estimates themselves are unlikely to respond to the data – explaining the methods and results, their strengths and weaknesses, is a necessary first step.

All of this suggests the critical importance of an issue that is not often discussed or researched – how to present value-added data to teachers in the most useful manner. Although a full discussion of this issue is beyond the scope of this post, a few quick suggestions, based on the discussion above, might include: a clear description of the methods and how to interpret the results, along with ongoing reach-out for training and a means (e.g., a “hotline”) for teachers to ask questions; presenting error margins for each estimate (so teachers know when results are still too imprecise); and disaggregation of estimates by student subgroup.*

The majority of teachers, even those who are strongly skeptical about value-added, have long used testing data productively. Tests have always been used to diagnose student strengths and weaknesses, and skilled teachers have always used these data to help improve instruction. Value-added estimates could add even more useful data to that arsenal of information.

Hopefully, these productive low/no-stakes uses for value-added have not been drowned out by all the controversy over its high-stakes use. Research and policy should start focusing on the former as well.

- Matt Di Carlo


* Many states and districts using growth model estimates produce some form of "teacher report." My (admittedly limited) review of a few of these suggests that they vary quite widely in how they present the data, as well as in their descriptions and guidelines for interpretation. I might explore this more thoroughly in a future post.


I don't get it, Matt. You say VAM can be useful and also say it lack utility.

Which is it?



I don't understand your question. When did I say it lacks utility?



"Granted, a big problem is that value-added models are not actually designed to tell us why teachers get different results – i.e., whether certain instructional practices are associated with better student performance." Teachers spend all day inside the "data" and are constantly disaggregating it. You seem to be saying that there is some hidden information in the VAM that cannot be gleaned any other way. Are you talking about what can be gleaned to help kids or help bosses write up teachers? In all my years inside the classroom not once did I need to look at the data from a standardized test to know what each student needed. Yet, you think it can help me. I have no idea why you think that. And, you wrote this: "For instance, if a teacher is told that her English language learners tend to make less rapid progress than her native speakers, this is potentially useful" Do you honestly think She doesn't know this and need the data so she can estimate something? I mean, really, this is the height of reaching. If a teacher of non-native English speakers, or anyone with a knowledge of how f****** hard it is to learn a new language, doesn't already know that the ELLs will make "less rapid progress" they should be fired. You are a conundrum to me, Matt.


I believe that VAM does give some information that the teacher did not know: how their students do relative to the rest of the district/state with students like them. It is not possible for an individual teacher to know this without VAM or other types of statistics.

TFT, it may in fact be useful to know that my ELLs are making better progress than the rest of the state because it tells me that I am doing something right even though it is super frustrating on those days where it seems like they don't get anything. Yeah ... they seem to grow slowly on the tests but I know they are growing faster than most other ELLs... I have not won the war of getting them to where they need to be but I have won a small battle of getting them there faster.


Faster is better? I think, Andrew, that you are confusing speed with depth, and that's pretty dangerous.

And knowing that my kids are getting there faster means nothing. Too many factors exist outside of the school to make that information useful.

Tell me, are you a teacher, or is this just surmising on your part?


I remember the first time I was presented with my value added scores. My students had made great progress in reading, but I was mediocre in math and language, and my student's science scores were an embarrassment. I suppose I could have been defensive. Instead I went home and googled "teaching best practices" and generally read everything I could get my hands on about how to improve my teaching. It really made a difference. I teach in a high needs school with a large number of ELL students and they do very well. Even without disaggregated data, I found my VAM very useful. I am impatient with people who whine about getting a low VAM. It's not the end of the world. If you really care about your students, you'll try to help them grow. Blathering on about some invisible "depth" of learning that is supposed to be there just because you say so, won't help your students.


Ray, shouldn't you have read that stuff before you took responsibility for a classroom full of kids?

More importantly, maybe, is the fact that you were hired without the requisite knowledge you admit you lacked.