uses the HBO show The Wire
(excellent--Sarah and I highly recommend it) to make a general point on how performance measurements often corrupt the very process they were meant to measure:
It happens everywhere. A perfectly useful measurement gradually becomes more important that it has any right to be and soon everyone's life is shaped by the slightest variations in that measurement. People quickly figure out how to improve their "score" in dozens of ways that do not improve the performance or outcome that score was originally designed to measure and the institution eventually takes on the character of those whose power and influence rises because they are particularly skilled at gaming the stats.
Note: Sarah and I watch The Wire
on DVD via Netflix, so we just finished season three. Please, no spoilers from the current season.