A push by some charter advocates resulted in a last-minute amendment to House Bill 2 which may introduce the “California Similar Students Measures” (CSSM) into Ohio’s school-accountability system. This is an entirely unnecessary effort, and CSSM should not be implemented in the Buckeye State.
The California Charter Schools Association developed CSSM, a simple regression model that uses school-level data, to approximate a value-added student growth model. The reason: California does not have an official student growth measure. CCSM is an improvement over using only a school’s raw proficiency results to evaluate schools, and the organization deserves credit for implementing it in California. However, a CSSM-like analysis should only be used in the absence of a proper student growth measure—and as such, it has no place in Ohio.
Ohio legislators should read very carefully CCSA’s own caveat emptor (emphasis added):
While CCSA believes these metrics [CSSMs] are an improvement on the existing measures in law for charter renewal, longitudinally linked, individual student growth data is the ideal source for most appropriately assessing a school’s performance. Because the Similar Students Measure is calculated with aggregate school-level data, it is an approximation of value-added modeling. True value-added modeling requires individual student data connected to the schools...