Ask most executives the purpose of performance appraisal and they'll tell you: "to give feedback to my employees about their performance with the aim of improving it." I believe these executives are almost entirely wrong.
As B. F. Skinner and his disciples have demonstrated empirically, the more time that elapses between behavior and its consequences, the less those consequences shape future behavior. Thus, the typical annual performance appraisal has almost no utility as feedback directed at improving behavior. This is because too many weeks or months have elapsed between the behavior and the time employees learn their manager's reaction to that behavior.
The only actual utility of formal annual performance appraisal is to document feedback that has already occurred during the year. In other words, virtually every sentence or paragraph should begin with the words "As I told you on (insert date), ..." A formal performance appraisal should only contain things the boss and subordinate formerly discussed at the time they took place. Ideally, employees would see nothing in the appraisal document that they hadn't already heard from the boss some weeks or months ago.
In order for this documentation to occur, bosses must be communicating with their employees on a regular basis about their reactions to the employees' work. For busy bosses, this is difficult to do but absolutely essential. And it doesn't need to take much time, a quick "nice work on that report you gave me yesterday" or a "you need to put more effort into getting me that report on time" should do it. Also, bosses need to log such comments when given so they can include them in annual performance appraisals.
