While using performance appraisals is a useful tool, it does have some problems.
1. In and of itself PA's and any associated monetary gain do not actually encourage performance excellence. The feedback and consequences occur far too long after the desired behaviors and habits are supposed to occur (usually six months).
2. It is best when trying to determine who one should be given greater responsibility.
3. PA's often measure normative behavior, that is, behavior the person is supposed to be doing anyway, rather than encouraging excellence.
4. PA's, unless the actual PA interview is truly a give and take interview do not do a good job of identifying factors that are interfering with a person's performance.
In terms of 1-3 may I suggest thinking in terms of a model that links behaviors to strategies and missions, such as Hoshin Kanri. (see attached)
May I suggest using a process called nominal group technique to ask the employees themselves what interferes with their striving for excellence and what helps them in their striving for excellence. (see attached)