Gates researchers: value-added works but needs help
TAMPA -- We weren't surprised to hear an endorsement of value-added methods during Friday's conference call on the Bill & Melinda Gates Foundation's study to videotape teachers in their classrooms across the nation.
After all, their research team led by Harvard's Thomas Kane has been among the leading proponents of value-added, which allows districts -- at least in theory -- to accurately predict each student's annual gains on test scores and judge teachers on their success at meeting those goals. (Hillsborough County is in the midst of designing its own value-added formula with backing from both national teachers' unions, as part of its seven-year, $202 million reform effort with the Bill & Melinda Gates Foundation.)
In Friday's call, Kane said the videotaping study offered further support for the idea that value-added measures are useful. But he agreed that such calculations can be quite volatile, showing significant differences from year to year or using different variables.
"There’s been a debate recently about whether value-added fluctuates too much, (or) is too imprecise to use for evaluation purposes," Kane said. "We found about the same degree of volatility that everyone else...has found. It’s just that things are not so volatile that they’re not predictive. It’s not perfect, there is some fluctuation. But it does give information.
"Our goal shouldn’t be to continue debating whether value-added scores are volatile or not," he added. "They are volatile. The answer is to add in other measures to determine whether a teacher is effective."
For more details on what Kane's team has found in preliminary results on the videotaping study, Measures of Effective Teaching, here is a research paper and one suggested approach for developing an evaluation system that uses value-added techniques.