Value-Added Measures: What's It All About?
by UCLA IDEA
Themes in the News for the week of May 23-27, 2011
With Memorial Day signaling the approach of summer, we start to look back on a school year that has brought massive and unfairly distributed financial uncertainty to public schools. One of the biggest education reforms on the horizon, however, does little to address basic school problems of overcrowded classes, insufficient textbooks, impoverished students, narrowed curriculum, deteriorated facilities, and ultimately, teacher, school, and community accountability.
Called “value-added measures” (VAM), this method offers simple-sounding, “common sense” explanations and justifications. By testing students at two or more points of time, VAM designers attribute higher-than-expected gains in student scores to “effective” teachers and lower-than-expected gains to “ineffective” teachers. Designers claim to account or control for influences on student learning that originate outside the classroom and are not under a teacher’s control (i.e., different family resources, previous instruction, outside support, etc.)
Relying on VAM, school leaders can use test scores to decide which teachers to fire, to promote or to reward with salary increases or bonuses (New York Times, Washington Post). Spinoffs include financial incentives not only for teachers, but for students as well (Los Angeles Times).
However, taking a closer look at VAM, the method unravels (Education Nation). With current testing knowledge and resources, VAM formulas cannot possibly "control" for all the factors influencing student growth. For example, school administrators often follow parent preferences in making or switching class assignments. If a teacher is assigned a class with a disproportionate number of high-achieving students, other students who are low or average achievers in that class can show greater gains than if their classmates were randomly selected. These "peer effects," introduced by selective sorting, can distort judgments about teacher effectiveness.
The use of VAM will likely lead to a number of unintended consequences, not least of which is to encourage even greater focus on testing. Student tests that feed into the VAM systems are already heavily criticized for narrowing curriculum, distorting what teachers teach and ignoring much important learning that schooling provides.
Even greater problems arise when VAM is used to create a shorthand public impression of a teacher's overall teaching worth--such as when individuals' scores are published in newspapers. Such actions are not only counterproductive in their own right, they sap the resources and attention that might otherwise go to real educational improvement.