Ask most working people the purpose of performance appraisal and they'll tell you it is done so they can find out how they're doing at work. In other words, as a source of feedback from their boss.
Unfortunately, to the extent that the performance appraisal reflects qualitative judgments today about performance that occurred several weeks or months ago, the feedback is absolutely pointless. That is to say, worthless as a shaper of the employee's future behavior.
B. F. Skinner and his colleagues demonstrated conclusively that the more time that elapses between a piece of your behavior and another's reaction to that behavior, the less that reaction shapes your future behavior. In the case of performance appraisals, which are often done at six month or one year intervals, simply too much time has elapsed for the 'feedback' to be useful.
So...why do firms do performance appraisals? Their only true use is as a process that documents in writing what the supervisor has already told the employee about his or her behavior at the time the behavior occurred. In fact, a firm should probably require every evaluative statement in the appraisal to be preceded by the clause "As I told you on (insert date), ...."
There should be absolutely no surprises in your performance appraisal. Everything should be reminders of former conversations with your boss. If there are surprises in your performance appraisal, they won't change your behavior but they will irritate you. It is like what they say about trying to teach a pig to sing. You won't succeed but you will surely irritate the pig.
