The apparent sticking point in the negotiations is whether a teacher’s contribution to student learning as measured on standardized tests will play a meaningful part in that teacher’s evaluation. Mayor Rahm Emanuel would base a teacher’s evaluation in part on a statistical analysis that estimates the measurable contribution a teacher makes to student test score growth during the year. This is commonly known as a value-added assessment. Teachers argue that value-added is an unreliable measure of their effectiveness and shouldn’t be used in their evaluations.

From the students’ perspective, what matters is whether these value-added models contain information that improves the school system’s ability to identify and remove ineffective teachers. In a new report for the Manhattan Institute, I provide evidence that value-added passes this test.

Let me be clear: These are teachers you would not want teaching your child. These are bad teachers.

Though all agree that value-added is an imperfect measure of teacher quality and should never be used in isolation to make employment decisions, my analysis clearly shows that the procedure contains information that can be used to better distinguish between effective and ineffective teachers. My results are consistent with prior research by economists Dan Goldhaber and Michael Hansen using data from North Carolina.

Teachers say that they are worried about using an imperfect measure like value-added to assess performance because some teachers will receive scores that are lower than what they truly deserve. But no evaluation system is perfect. What’s lost in this critique is that the current teacher evaluation system is also riddled with error. It’s just that the systems in place in Chicago and around the country default in the interest of teachers and against the interests of students. Incorporating value-added into the evaluation process would help to reverse that.

Clearly, more than a few low-performing Chicago teachers are getting higher ratings than they deserve under the current system. That’s error. The difference between the current system and that of value-added analysis is that right now the error is resolved in the teacher’s favor. But it’s an error that hurts the students who are later assigned to those low performing teachers.

Too often, the rules that govern public schools favor the adults at the expense of the students. Using objective measures of student performance to inform — not replace — current evaluation systems is a step toward a system that puts students’ interests first.

Original Source: http://www.usatoday.com/news/opinion/forum/story/2012-09-13/chicago-teachers-strike-testing/57778960/1