Value Added Measurements Work and Tell Us a Lot About Teachers.

I don’t know how I missed it  but an article in Jan. 6 New York Times, and the research report* that was its source, provided some definitive answers to a major question in teacher evaluation.
Race to Top guidelines insist that teacher evaluations must include students’s test scores. A major complaint of this approach is that it’s unfair to teachers who have struggling learners in their classes.
What convinced me that student test results should  be included, however, was Valued Added metrics=VA (See my blog on Dec.13, 2011). VA takes into account data on the students past test performances, their personal background including family make-up and economic status to predicts student outcomes on tests. If the student performs better than the predictions this is the value added by this year’s teacher.

But controlling for numerous factors, including students’ backgrounds, the researchers found that the value-added scores consistently identified some teachers as better than others, even if individual teachers’ value-added scores varied from year to year.

There are no absolutes in this process and a teacher whose students have higher scores will not automatically be evaluated better than a teacher whose students have lower scores but who were predicted to do even worse.

Opponents of this approach argue that it’s inconsistent and does not always make an accurate assessment. Unions in particular have resisted the use of VA metrics in contacts but Washington, D.C. (about which I wrote last week) among others is using it.
The study to which I referred was done by three economists determined not only that VA results were significantly accurate but that in addition by looking at 20 years of data of 2.5 million students that teachers who regularly show value added  impact the lives of their students for many years.

After identifying excellent, average and poor teachers, the economists then set out to look at their students over the long term, analyzing information on earnings, college matriculation rates, the age they had children, and where they ended up living.

The results:

Students with top teachers are less likely to become pregnant as teenagers, more likely to enroll in college, and more likely to earn more money as adults, the study found.

Even if VA not perfect the study authors recommend it’s use in determining the hiring and firing of teachers.

The authors argue that school districts should use value-added measures in evaluations, and to remove the lowest performers, despite the disruption and uncertainty involved.

“The message is to fire people sooner rather than later,” Professor Friedman said.

Professor Chetty acknowledged, “Of course there are going to be mistakes — teachers who get fired who do not deserve to get fired.” But he said that using value-added scores would lead to fewer mistakes, not more.

I’ll be interested to hear how the unions try to get around this study.

*The report site includes a video of one of the authors presentation of the study.