Have you ever sat down to do a certain employee's performance review and felt the urge to blast them in terms of ratings even though they do a pretty darned good job? Or how about the employee you seem to have a special place in your heart for? Do you feel compelled to give them better ratings than they really deserve because you like them?
These aren't necessarily uncommon occurrences in the world of conducting employee evaluations. Human nature being what it is, it can be tough at times to maintain a reasonable level of objectivity. The employee who is less likable, at least from your vantage point, can get cheated out of accurate ratings simply because your negative bias creeps into the process. On the other hand, that employee who may be a great diplomat and, well let's just say it, butt kisser, might garner more positive ratings than warranted.
So how do we avoid falling into the trap of being overly subjective in reviewing employees? The first step is to focus on the employee's positive work attributes. Do they do their jobs well? Do they bring certain skills to the team that are important to overall success? Are there skill or behavioral deficiencies that need to be enhanced? If so, specifically what are they?
Think in terms of the work they do and the workplace behavior for each employee being reviewed and focus less on whether the employee is cool or funny or geeky or socially awkward. Without question, if coaching to be a more effective communicator, for example, is needed, don't avoid going there. But don't let your perception of their personality traits influence your ratings of the employee in a more dramatic manner than necessary.
Now we all understand that there are the obnoxious or arrogant or irritating employees among us at times. The key with those people is trying to coach them to minimize those "behaviors" and make them less overt in the workplace. The more effective you are in coaching those "behaviors" out of the employee over time, the less they will subconsciouly creep into your perception and, therefore, evaluation of their work.
In short, take a step back when looking at how employees truly perform. Try your best to put those personal biases aside and maintain as much fairness as possible. Sometimes that is easier said than done, but your own credibility is at stake. Discounting the notion that you could be introducing undue bias into the process is potentially harmful to your reputation as an effective manager.