NJ Teacher Evaluation: Math Fail #1
Do the Broad-funded interns at the New Jersey Department of Education understand math?I ask because their disastrous teacher evaluation proposals, announced with great fanfare last week, betray an embarrassing misunderstanding of the fundamentals of mathematics. It will take a few posts to catalog them all, but let's start with this:
A large portion of a "tested" teacher's evaluation will now include a metric called a "Median Student Growth Percentile," or mSGP. In a previous post, I showed how SGPs are woefully inappropriate for use in teacher evaluation, because they are purely descriptive measures: they do not measure how a teacher contributes to student learning.
But even if we put aside the problems of SGPs, there are still obvious problems with mSGPs; obvious, that is, to anyone with a basic understanding of the difference between a median and a mean.
