There is mixed evidence, however, that experience and education levels are associated with student learning (Goldhaber, 2002; Goldhaber and Brewer, 1997, 2000; Hanushek, 1997; Wenglinsky,2002).[1] Student achievement is measured through the use of standardized tests to determine the academic growth of students over time. Recently, a type of analysis of this growth termed "value-added modeling," following the 1971 approach of Eric Hanushek,[6].has sought to isolate the fraction of student achievement gains attributable to individual teachers, or in some cases groups of teachers.[7]