Are some rating systems more objective than others?
Not all employee rating systems are equal. The degree to which a rating item yield objective results (and useful information) depends on what we call the "stem" of the item.
The stem of an item is the description attached to the item -- the description of what is to be rated. For example, imagine an item that says" "Is an effective team member". The manager is asked to rate the employee on this element using a seven point scale that runs from "never" to "always".
The stem (is an effective team member) is completely vague and makes no references to measurable behavior or employee actions. As a result the rating reflects the manager's biases and subjective interpreations of what an "effective team member" means, much more than it reflects any reality about the employee. In fact, with such vague stems, different managers seeing exactly the same employee actions, will give entirely different ratings for the same employee.
If the stem is much more specific, or behaviorally anchored, then there is less room for interpretation of the meaning of the item, although it's still subjective. For example, if there were several separate and specific items for rating, things can be improved. Let's say we have a stem that says: "Offers advice to other team members," or, "Volunteers to help team members when time permits". These are much more specific. There is less subjectivity to the rating because they refer to specific behaviors (offers advice, volunteers).
The more specific, and the more the stem refers to employee behaviors, the easier it is to remove some of the subjectivity involved.