Since last week’s LA Times article hit the press, some of the nation’s experts on value-added methodology (VAM), like Doug Harris, and advocates for their use, like Rick Hess, have challenged the newspaper's decision to publish individual teachers’ ratings. Both are quoted in Carl Bialik’s thoughtful critique in the Wall Street Journal, where he concluded that the metric being used is way too unstable to give consistently accurate results of which individual teachers are more effective than others.
Even Dan Goldhaber, a well-known labor economist who routinely develops and uses these tools in education contexts, “strongly opposes” making individual teachers' value-added scores public in the way done by the LA Times. In recent comments on the Web, Goldhaber noted that there are “legitimate reasons” — like pull out programs and migration of students in and out of individual teachers’ classrooms (which is very common in LA) — that “make the attribution of student (achievement) to (specific) teachers complex.”
The VAM tool can be very useful in helping teachers get better at what they do, as also suggested by the new Song, et. al. LA Times article. And the district and the union in Los Angeles should find a way to use value-added data to help teachers improve their teaching practice and spread their expertise. However, as an isolated metric, VAM is not a fair method (as some policy pundits and policy zealots suggest) to praise or condemn individual teachers.
Reformers have long yearned for tools to turn teaching into a results-oriented profession. I am one of them. But the growing enthusiasm for using value-added formulas to offer summative judgments on the effectiveness of individual teachers is unwarranted, when research shows that 25-30% of those identified as effective in one year would be identified as ineffective the next.
The policy and media voices advocating for the indiscriminate use of VAM tools remind me a bit of “the madding crowd's ignoble strife” described by 18th century English poet Thomas Gray. And I also recall the comment of Scottish historian Charles Mackay, who once observed:
Men, it has been well said, think in herds; it will be seen that they go mad in herds, while they only recover their senses slowly, one by one.