Reference #91: Reinventing Performance Management
Much of a performance rating reveals more about the rater than the person being rated. For example, how valuable a rater views strategic thinking significantly affects their assessment of someone else's strategic thinking. This is known as the "idiosyncratic rater effect".
Shifting the rater's focus from the individual to a question of their own future actions regarding that person reduces this effect. You produce more consistent results by asking, for example, asking whether you would always want them on your team, or whether they are ready for a promotion, rather than by asking external focused questions.
Buckingham, Goodall. Reinventing Performance Management, 2015. Reprinted in Reinventing HR, 2019. (49, 51-52)