Open Letter to Legislators on Use of Test Scores

Scores are unstable

The problem with acquiescing to the Federal demands for using test scores to evaluate teachers is in the fundamental assumption in the use of VAM scores. That assumption is that "teacher effects are a fixed construct that is independent of the context of teaching, and stable across time."  ("Value-Added Modeling of Teacher Effectiveness: An Exploration of Stability across Models and Contexts", Education Policy Institute) 

New York University economist Sean Corcoran explains it this way.  The “margin of error" is so large that a teacher at the 43rd percentile might actually be at the 15th percentile or the 71st percentile.”  Both the Economic Policy Institute and the National Academy of Sciences frown on the use of value-added in decisions involving teachers, due to the imprecision of the measures.  And finally, it should be remembered that use of these scores can misidentify a good teachers as a bad teacher or a bad teacher as a good teacher. 

Such instability is not useful in building policy and accountability.  

Scores not applicable to all teachers or available in a timely manner

With that issue in mind, I bring to your attention a chart, found on page 47 of the OSPI report entitled “Washington State Teacher and Principal Evaluation Project:  Including Student Growth in Educator Evaluation.”  

http://tpep-wa.org/wp-content/uploads/TPEP_Module-Student_Growth.pdf

This report states that using the test scores model provides test data that’s relevant to only 16% of Washington’s teacher, while there is no relevant data on the remaining 84%.

In addition, teachers are evaluated in May, but test score data is not available until Sept or Oct.  Student growth data is designed to be calculated from year to year, but the tests from which the data are derived are given only every other year; eg eighth grade and then tenth grade. 

These constraints make application of student test scores both impractical and unprofessional.

There is a viable alternative

Much of the objection raised by supporters of using test scores to claims of their unreliability is based upon the false assumption that there is no viable alternative.  AT least here in Washington, there most certainly is a viable alternative that will apply to all teachers.  That would be the new teacher/principal evaluation protocols going online statewide this school year.  They have been researched, developed, drafted, and piloted by numerous education association/school district consortiums across the state. 

We need not incorporate student test scores in the belief that there’s no alternative, because one exists and deserves a chance to be used