The sage on the stage – “teacher know it all” era of education has gone away long time ago despite the the tradition still prevails in many of the World’s classrooms. One thing which ponders me most with this development is how to evaluate teachers’ outcome as it is very widely being practiced in the name of maintaining quality and standards. The new teachers evaluation process-the value added model is using this artificial mathematical construct to evaluate teachers : y = Xβ + Zv + ε where β is a p-by-1 vector of fixed effects; X is an n-by-p matrix; v is a q-by-1 vector of random effects; Z is an n-by-q matrix; E(v) = 0, Var(v) = G; E(ε) = 0, Var(ε) = R; Cov(v,ε) = 0. V = Var(y) = Var(y – Xβ) = Var(Zv + ε) = ZGZT + R. value-added analysis involves looking at each student’s past test scores to predict future scores. The difference between the prediction and students’ actual scores each year is the estimated “value” that the teacher added — or subtracted.
This is a bizarre calculation. You are trying to exclude all other factors in the life of the student and try to force your data to speak only and only about teachers’ input. Hey, I damn didn’t like the way my professor teaches my statistics class. I barely listen what he talks in class. I came to realize that it barely touches me. Hence, I have to go elsewhere where they do the job of teaching statistics in a much more sense-making way, to the http://www.khanacademy.org/. Now, I understood many of the concepts in that course very well. For that matter I also scored 100 in series of homeworks and exams. Now, am I going to attribute my success to my professor or to the Khan academy? Well, in the eye of the Value add model, yes indeed it is the professor’s input. But in my understanding, I wouldn’t exclusively attribute it to the Khan Academy. It rather is a product of many many factors, Khan Academy is just one. How many times I went online to look for explanations for a concept or an idea. Quite often. How many times I had discussed with friends, quite a lot. So, my point is that is it really possible and even is it legitimate to think that a student performance in a given course is exclusively the result of what happened in that course? I doubt it!