- William Sanders (statistician)
Dr. William L. Sanders is a senior research fellow with the
University of North Carolinasystem and is manager of value-added assessmentand research for SAS Institute Inc. in Cary, North Carolina
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. This system has been used in
Tennesseesince 1993, and has been adopted by a number of other school districts across the United States. Sanders' approach has been used to support the theory that the quality of teachers is central to educational achievement. [ [http://www.city-journal.org/html/11_3_why_merit_pay.html Why Merit Pay Will Improve Teaching by Steven Malanga, City Journal Summer 2001 ] ]
He received his bachelor's degree and doctorate from the
University of Tennessee, Knoxville.
He assumed the SAS position in June 2000, upon retiring after more than 34 years as
professorand director of the University of Tennessee's Value-Added Research and Assessment Center. Sanders was the Jason Millman Memorial Lecturer at the National Evaluation Institutein San Jose, California(July 2000).
Sanders has served as an advisor to policy makers at the federal level; he has worked with many states and districts interested in developing a value-added component to leverage their testing data into more precise and reliable information for better decision making. Many of his suggestions concerning measurement of outcome were incorporated into
Tennessee's Educational Improvement Act (1992) and more recently in legislation creating pilots in Coloradoand in a statewide accountabilityprogram in Ohio. Pennsylvaniaand New HampshireDepartments of Education sponsor pilots, and the Iowa School Board Associationsponsors his value-added work in that state. Battellefor Kids funds the SAS EVAAS services for the participating districts in Ohio.
Over the last twenty years, Sanders and his colleagues have developed and refined a methodology to measure the influence that school systems, schools and teachers have on the academic progress of students. By following the academic progress of each student over time and using statistical
mixed-model techniques, Sanders has demonstrated that both accelerators and impediments to sustained academic growth can be measured in a fair, objective and unbiased manner. His value-added approach to assessmentprovides crucial diagnostic information for principals and teachers and can also be used as the basis for district or state accountability models.
To accommodate the technical requirements of a mixed-model application of the scope of SAS EVAAS, Sanders and his colleagues have developed a software system capable of solving thousands of equations iteratively. This complex system enables a massive multivariate,
longitudinal analysisusing all achievement data for each student, even those with incomplete testing histories, to estimate the effects of teachers, schools and school systems. The development of this software has allowed the inherent advantages of longitudinal analyses to be extended to a statewide application, previously unavailable from commercial software. Compared to simpler approaches to educational value-added assessment, the SAS EVAAS system offers a number of advantages.
“Using mixed model equations, TVAAS uses the
covariance matrixfrom 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." [http://pareonline.net/getvn.asp?v=10&n=11] The model focuses on academic gains rather than raw achievement scores.
Dr. Ballou, in Lissitz (Ed.), 2005, "Value Added Models in Education: Theory and Applications," analyzed the TVAAS and determined that value added-assessment of teachers are fallible estimates of teacher contribution to student learning, stating that
standard errors of value-added estimates are large. Author thinks that value added models are merely one useful tool that should be used as one of many assessments in a comprehensive system of evaluation.
Researchers from the
RAND corporationstudied Dr. Sanders' method and determined that his approach does not satisfactorily account for bias, cautioning that non-educational effects may be attributed by mistake to teachers, with no way of effectively determining the magnitude of the error. [ [http://www.rand.org/pubs/monographs/2004/RAND_MG158.pdf Evaluating Value-Added Models for Teacher Accountability ] ] Ballou (2002) and Kupermintz (2003) further support this claim, claiming that non-educational factors have a noticeable impact on the evaluation of teachers despite efforts to account for them in the model. [ [http://harcourtassessment.com/NR/rdonlyres/2C54ADBA-9959-4F82-82B3-8E65FB822088/0/ValueAdded.pdf Contemporary Report ] ]
Standardized testing and public policy
* [http://www.city-journal.org/html/11_3_why_merit_pay.html Why Merit Pay Will Improve Teaching] - Steven Malanga
* [http://www.cgp.upenn.edu/pdf/Braun-ETS%20Using%20Student%20Progress%20to%20Evaluate%20Teachers.pdf - Review of strengths & weaknesses for various value-added assessment systems]
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