NCPA's Value-Added Assessment
July 9, 2003
All states should incorporate value-added assessments in their school evaluations because measuring schools based on passing rates does not reveal whether they are improving their students' scores. Thus, schools currently identified as "successful" may simply be benefiting from inheriting very able students. That is hardly a model lower-performing schools can copy, says NCPA Policy Analyst Matt Moore. Furthermore, a school may be good at serving some student populations, but not others.
Value-added analysis removes factors that affect performance such as a student's background and family characteristics through state-of-the-art statistical regression. This allows researchers to isolate and measure the school's effect on a student's performance from one year to the next. The NCPA's Report Card on Texas Schools examines student-level data and performance on the math and reading sections of the Texas Assessment of Academic Skills for three school years (1999-2002).
The scores of sixth grade student in Dallas-area public schools, for example, show that:
- Only one school in the Dallas area ranks in the top 10 in serving all its student populations.
- By contrast, 41 schools are in the top 10 in serving at least one student population.
- Likewise, a comparison of the top 100 schools in Texas based on raw scores and the top 100 based on value-added finds only 12 schools on both lists.
Parents should be able to send their children to the school that is best for their child, says Moore.
Source: Matt Moore, "NCPA's Value-Added Report Card on Texas Schools: A Model for Meaningful Assessments," Brief Analysis No. 446, July 9, 2003, National Center for Policy Analysis.
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