This is an excellent piece and a must-read. It highlights advocacy journalism in the service of the “value-added” agenda at the Los Angeles Times (and an ongoing attempt at the NY Times) to release rankings of teachers based on the changes in standardized test scores of their students.

First, only a fraction of a district’s teachers are included—only those who teach reading and math; there are no standardized tests for other subjects. No allowance is made for many “inside school” factors, such as the effect of team teaching, after-school tutors, substitute teachers, a child or a teacher who is absent for long periods of time, or an unstable school environment—a new principal, a violent incident, a district overhaul. And finally, critics ask: Since the number is based on manipulating one-day snapshot tests—the value of which is a matter of debate—what does it really measure?

Research experts weighed in from all directions in response to the Los Angeles Timesproject, some saying value-added rankings may be flawed, but they are better than nothing; others said the numbers are only reliable enough to evaluate schools, not teachers. In February, two University of Colorado, Boulder researchers caused a dustup when they called the Times’s data “demonstrably inadequate.” After running the same data through their own methodology, controlling for added factors such as school demographics, the researchers found about half the reading teachers’ scores changed. On the extreme ends, about 8 percent were bumped from ineffective to effective, and 12 percent bumped the other way. To the researchers, the added factors were reasonable, and the fact that they changed the results so dramatically demonstrated the fragility of the value-added method.

But here is perhaps the most telling observation: nearly every economist who weighed in agreed that districts should not use these indicators to make high-stakes decisions, like whether to fire teachers or add bonuses to paychecks. The numbers, they said, can’t carry that kind of weight. By last summer, it should be noted, Michelle Rhee had already fired twenty-six DC teachers based in large part on low value-added scores. And New York City wants principals to use them immediately for tenure decisions.

Read the rest of the article here.