If this becomes policy, it will most likely become another example of Goodhart's law. http://en.wikipedia.org/wiki/Goodharts_law http://en.wikipedia.org/wiki/Go

If this becomes policy, it will most likely become another example of Goodhart's law. http://en.wikipedia.org/wiki/Goodharts_law http://en.wikipedia.org/wiki/Goodharts_law You can find a measure that correlates to performance, but once you use it to actually evaluate teacher, teacher will adapt and the measure will lost all relevance. Rely on test scores? Teach the test, not the material. Rely on student evaluations? Bribe them with easy material and good grades. Rely on principal evaluation? Get on its good side.