Problems with Percentiles: Student Growth Scores in New York’s Teacher Evaluation System

New York State has used the Growth Model for Educator Evaluation ratings since the 2011-2012 school year. Since that time, student growth percentiles have been used as the basis for teacher and principal ratings. While a great deal has been written about the use of student test scores to measures educator effectiveness, less attention has been paid to how value added models have played out in schools, school districts, and states since their widespread adoption associated with Race to the Top. This study employs univariate and multivariate statistical procedures to examine model results at the student level in one district, and across districts, and identifies problems associated with the model. Policy implications and recommendations are discussed