And how are you supposed to measure performance? Many jobs are just not susceptible to doing that. It is well known in the software industry that attempts to me

And how are you supposed to measure performance? Many jobs are just not susceptible to doing that. It is well known in the software industry that attempts to measure programming performance result in programmers skewing their efforts in order to make the metrics look better. Teachers in the UK are measured on students' grades, so for some <sarcasm> totally unrelated reason </sarcasm>, students grades have gotten better every year for the last 20 years. Proven ability to do your job is one thing; measuring your individual performance whilst doing it is another thing altogether.