Report: Student Test Data Predicts Teacher Quality

Published September 5, 2012

Statistical analyses of student scores can accurately rate teachers’ effectiveness in instruction, according to a new report published by the Manhattan Institute for Policy Research.

The report, by Marcus Winters, reviews a method of evaluating teachers called value-added modeling, which has sparked some controversy. VAM analyzes test scores as students progress through school to discover how a particular teacher contributes to or detracts from students’ progress.

“VAM is not a perfect measure of teacher quality because, like any statistical test, it is subject to random measurement errors. So it should not be regarded as the ‘magic bullet’ solution to the problem of evaluating teacher performance,” the report says. “However, the method is reliable enough to be part of a sensible policy of tenure reform—one that replaces ‘automatic’ tenure with rigorous evaluation of new candidates and periodic reexamination of those who have already received tenure.”

Winters notes current teacher tenure policies do little to remove poor teachers, who are associated with students’ higher rates of teen pregnancy, decreased chances of attending college, and reductions by as much as a grade level of learning from pupils in each school year.

“Transforming Tenure: Using Value-added Modeling to Identify Ineffective Teachers” analyzes data from Florida Public schools and concludes a third-year teacher’s VAM score reliably predicts his or her fifth-year teaching success. Winters notes researchers have found similar results using data from North Carolina.

He also found, as research has shown previously, that having a master’s degree does not improve teachers’ performance, on average.

Policy Considerations
Winters then considers the implications of his findings for tenure reform. He recommends teachers be repeatedly evaluated to retain tenure, as teacher effectiveness may fade.

He evaluates the outcomes of different ways to use VAM in tenure policy, concluding that removing teachers who consistently perform poorly—each year for, perhaps, a period of three years—mitigates the possibility of too quickly removing teachers who have simply had a bad year or received an inaccurate assessment.

“VAM, when combined with other evaluation methods and well-designed policies, can and should be part of a reformed system that improves teacher quality and thus gives America’s public school pupils a better start in life,” he concludes.


Learn more:
“Transforming Tenure: Using Value-added Modeling to Identify Ineffective Teachers,” Marcus Winters, Manhattan Institute, September 5, 2012:



Image by Jordanhill School D&T Dept.