In the world of scholarly statisticians consisting of Fisher,Bayes,Gosset and many more, the name William Sanders does not ring a bell, even for some of those in the statistical field. Well, even a simple Google search lists him third, after a writer and basketball player of the same name. Nevertheless, his contribution to the American education system has left a long lasting impact.
Sanders, born in 1942, was raised in a small dairy farm in Tennessee. He earned a doctorate in statistics and quantitative genetics from the University of Tennessee.
In 1982, Sanders came across a newspaper article about the then Governor Lamar Alexander’s plans to introduce merit pay for the best schoolteachers. But this, raised questions regarding the way in which the teachers’ merit would be measured.
Sanders devised a method called the Tennessee Value Added Assessment System, for measuring a teacher’s impact on the student’s performance, by incorporating various factors such as past performance, talent, wealth and home environment.
An excerpt from an article by Kevin Carey, which was published in The New York Times:
To fairly evaluate teachers, Mr. Sanders argued, the state needed to calculate an expected growth trajectory for each student in each subject, based on past test performance, then compare those predictions with their actual growth.
When he began calculating value-added scores en masse, he immediately saw that the ratings fell into a “normal” distribution, or bell curve. A small number of teachers had unusually bad results, a small number had unusually good results, and most were somewhere in the middle.
Sanders taught the world to quantify the difference between the great and the not-so-great teachers. Who would have thought that an unlikely combination of a Tennessee farmer turned statistician and a co-operative Governor (Ned McWherter) could bring about a sea change in the way schoolteachers were evaluated and paid.
The district of Tennessee still uses the method!