A short answer might be “inefficiently and unfairly.” Some police department, somewhere, may have a fair and effective evaluation system. I just haven't run across it yet. read more
Here are some of the things police are evaluated on: Reliability (is the officer on time and dependable), quality of report writing, personal stats (number of arrests, citations, parking tickets, warnings, etc), appearance (follows dress code), commendations, internal affairs complaints, time management, and peer relations. read more
Supervisors and officers tend to dislike dealing with performance evaluations (PEs) as much as they dislike internal affairs investigations and termination proceedings. Supervisors hate writing evaluations and officers hate reading them. But they persist anyway. read more