NYT economics columnist David Leonhardt with some VERY wise thoughts about value-added analyses and the LA Times story:

One way to think about the Los Angeles case is as an understandable overreaction to an unacceptable status quo. For years, school administrators and union leaders have defeated almost any attempt at teacher measurement, partly by pointing to the limitations. Lately, though, the politics of education have changed. Parents know how much teachers matter and know that, just as with musicians or athletes or carpenters or money managers, some teachers are a lot better than others.

Test scores — that is, measuring students' knowledge and skills — are surely part of the solution, even if the public ranking of teachers is not. Rob Manwaring of the research group Education Sector has suggested that districts release a breakdown of teachers' value-added scores at every school, without tying the individual scores to teachers' names. This would avoid humiliating teachers while still giving a principal an incentive to employ good ones. Improving standardized tests and making peer reports part of teacher evaluation, as many states are planning, would help, too.

But there is also another, less technocratic step that is part of building better schools: we will have to acknowledge that no system is perfect. If principals and teachers are allowed to grade themselves, as they long have been, our schools are guaranteed to betray many students. If schools instead try to measure the work of teachers, some will inevitably be misjudged. "On whose behalf do you want to make the mistake — the kids or the teachers?" asks Kati Haycock, president of the Education Trust. "We've always erred on behalf of the adults before."

You may want to keep that in mind if you ever get a chance to look at a list of teachers and their value-added scores. Some teachers, no doubt, are being done a disservice. Then again, so were a whole lot of students.

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The Way We Live Now

When Does Holding Teachers Accountable Go Too Far?

By DAVID LEONHARDT

Published: September 1, 2010

www.nytimes.com/2010/09/05/magazine/05FOB-wwln-t.html