What do you mean by Rating Scale in terms of performance appraisal?

the rating scale is the measurement of a certain task, it is a degree of effectiveness. most of the time a rating scale has an equivalent description,1-lowest and5 as highest.however in some ways you can have a descriptive rating scale and it will more specific. never, sometimes, often, most of the time and always. this is a more specific rating system that can be more objective.hope this can help.

The ratings scale is an objective method of rating an emploee. There is no scope of subjective appraisal.