Saturday, February 4, 2012

Flawed study mis-rates potential DC school closings

by Steven GlazermanFebruary 1, 2012 3:55 pm

DC would likely close some successful schools while expanding failing schools if it relies upon a study released last week. The much-anticipated study, which the Deputy Mayor for Education commissioned to help plan school closures and charter school policies, is highly flawed.

Photo by M.V. Jantzen on Flickr.

The goal of the study was to help DCPS balance out near-­empty buildings in some locations with over­crowded ones in others, taking into account the quality of the schools.

For all its colorful charts and maps, the report uses a faulty measure of school quality and does not make any serious attempt to predict how families and schools might react to the changes it proposes. With such important decisions at stake, the Deputy Mayor should insist upon more rigorous analysis.

The report authors crunched a lot of numbers in an admirably short period of time and produced some very interesting descriptive statistics, like the percentage of students below 185 percent of the poverty line in charters (75) versus DCPS (67).

The study counts, within each of 39 neighborhood clusters in the city, the number of "performance," or high quality, seats in schools and compares that to the number of school-age students living in that cluster. The difference is called a service gap.

It recommends schools for closure, or in some cases investment, to reduce these service gaps. But it doesn't justify the type of investment. Is it facilities? More teachers? Better teachers?

The authors define a "performance seat" as a seat in a school in the top tier of a 4-tier rating system they devised. Each school's tier comes from estimated percentages of its students who were judged "proficient" on the state assessment test in recent years, projected 4 years into the future assuming a straight line trend.

This study raises a lot of questions for most researchers and even lay readers. Two big flaws stand out, which are so basic and could do significant damage if city leaders overlook the problems.

It uses a flawed measure of school performance. At the heart of this paper is a 4-tier rating of school quality that relies on the percent of students who are proficient on the state test (called the DC-CAS). Never mind the fact that a proficiency rate throws away information by focusing only on whether a score was above or below a fixed cut point instead of how high or low it was.

Student proficiency rates have long been discredited as a school performance measure because proficiency rates capture student achievement at a point in time, but say little about how much the school or its teachers contributed to its current students' performance.

For example, a middle school could have declining proficiency rates if a feeder school begins sending more at-risk students to it, even if the teachers are especially skilled at working with a challenging population. READ the rest of the article by clicking HERE.

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