Of particular import to this study, is collider bias originating from stratification on retreatment variables forming an embedded M or bowtie structural design. That is, rather than assume an M structural design which suggests that "X" is a collider but not a confounder, the authors adopt what they consider to be a more reasonable…

States are increasingly interested in including measures of student achievement growth, or "value- added," in evaluating teachers. Annual state assessments, however, which are the typical measure of student growth, usually cover only reading and math teachers and only in grades 4-8. These state assessments thus cannot …

States and school districts are exploring alternatives to state tests for measuring teachers' contributions to student learning. One approach applies statistical value-added methods to alternative student assessments such as commercially available tests and end-of course tests. The evidence suggests that these methods can reliably distinguish…