William L. Sanders (26 April 1942[1] – 16 March 2017) was an American statistician, a senior research fellow with the University of North Carolina at Chapel Hill.
He developed the Tennessee Value-Added Assessment System (TVAAS), also known as the Educational Value-Added Assessment System (EVAAS), a method for measuring a teacher's effect on student performance by tracking the progress of students against themselves over the course of their school career with their assignment to various teachers' classes.
From 1972 to 2000, Sanders was a statistical consultant for the Institute of Agricultural Research, which is part of the UT system; he also was an adjunct professor in the school's College of Business.
"Using mixed model equations, TVAAS uses the covariance matrix from this multivariate, longitudinal data set to evaluate the impact of the educational system on student progress in comparison to national norms, with data reports at the district, school, and teacher levels.
[9] The accuracy of VAM for evaluating individual teachers has been further discredited by the Economic Policy Institute[10] and by mathematician John Ewing.