Lew Romagnano
President, Colorado Council of Teachers of Mathematics
CCTM President’s Column, September 2009
In August the Colorado Department of Education unveiled new ways of reporting CSAP data. The “growth model” allows CDE to report on the test-score gains made by individual students from year to year, and how these gains compare to those of other students at similar achievement levels. (The new reporting system may be found at www.schoolview.org .)
Until now, CSAP scores were used in several ways that are hard to defend. One approach is to compare schools’ performances on a given test. So-called “status models” simply compare the proportion of students at School A who score Proficient or better on a test with those at School B. This is done without considering the strong negative correlation between a school community’s socio-economic status (as measured by the proportion of students who qualify for free or reduced-rate lunch), and the proportion of students at that school who score proficient or better on the tests. The resulting “apples-and-oranges” comparisons have labeled many schools as failing even if many below-proficient students at a school grew tremendously during a school year from where they started the year, but not quite enough to reach the next achievement level.
A second way CSAP scores have been used is to measure a school’s yearly progress. This “cohort-to-cohort change model” compares, say, the 8th grade CSAP mathematics scores in a school from year to year. This ignores the fact that different groups of 8th graders are being compared each time.
The growth model seems much more likely than either of these models to detect the effects of high-quality instruction in a school or, some say, even in a classroom. Because of this, growth models or “value-added models” are important components of many education reform and accountability programs.