Well, my point wasn't that child abuse happens at whatever frequency, my point is that a whole universe of stuff happens that isn't captured by those statistics

Well, my point wasn't that child abuse happens at whatever frequency, my point is that a whole universe of stuff happens that isn't captured by those statistics. Again, I do think that some sort of unified performance measurement is important. But it's really easy to screw something like that up. Teachers spend between 5-35 hours a week with a student depending on schedule and we're summing up that interaction with information that fits on half of the back of a business card? That doesn't tingle your spider sense at all? "Warning, lots of information loss here"? When you base performance on a metric, then you re-orient everything around the metric. It is very very very important to get that metric right and a right answer probably doesn't fit in an HN post. I mean, nobody thinks engineers should be measured by kloc, let's not oversimplify for teachers either.