I'm saying that it is harder to measure and that the measurement is inherently noisier for teachers. We measure teachers by how their students perform on standa

I'm saying that it is harder to measure and that the measurement is inherently noisier for teachers. We measure teachers by how their students perform on standardized tests, which has all sorts of problems. The more important factor is the value placed on differential performance. A 10% difference in teacher performance is lost in the noise. It likely wouldn't mean more money even if it could be measured easily. Whereas a 10% difference in football might mean being #1 in the draft versus going undrafted.