| Re: Bell curve in performance appraisal Hi!
Let me just add and clarify some points on the explanation of Siva on the Bell Curve and Forced Ranking.
The Bell Curve usually refers to the "normal distribution curve". The word "bell" was derived from the actual appearance of the curve. Indeed, when all statitistical quantities are correctly distributed within the curve, its appearance will look like a "bell".
The quantities allocated by Siva in his example (20-70-10) would never result to a normal curve. Such statistical configuration is a "eschewed" curve even if viewed from any direction or angle. The normal distribution curve used by many multinational organizations would normally have five (5) or six (6) segments, with both the right and the left having the same quantities assigned. The middle right and left segments of the curve have almost the same quantities too. Hence, the actual perfect or nurmal curve would have the following quantities: 5-10-35-35-10-5
Many organizations like GE, Toyota, etc. would normally reward the top 5% and 10 % on the right side of the curve. Those 5% on the left side of the curve is usually "managed-out" when they fail to improve their performance after another or two (2) more appraisals--- depending on internal policy and labor law.
I also disagree with Siva's point that the ratings will just have to be inserted into the curve and it will find its place there. This view is not correct.
The reason why this method is called "forced ranking" is because all concerned employees evaluated are compared with each other and ranked to determine the best among the group. Hence, when a group is composed of 100 employees, these employees will be ranked from 100 to 1 and distributed according to the above percentage I mentioned above.
We must all understand that the Bell Curve or Forced Ranking is not an appraisal or perfromance management tool.
An appraisal refers to the evaluation of performance (or outputs) vis-a-vis agreed targets or goals. What the Bell Curve can do is simply to identify the best performer among those who were rated with "Outstanding" via comparison and ranking. This is usually done to determine who deserves promotion/ rewards or sanction for every performance period.
Best wishes.
Ed Llarena, Jr.
Managing Partner
Emilla Consulting
Manila, Philippines
Tel: 00632-905-3135
0063-916-762-7218
(helps improve corporatte governance worldwide, esp in Asia, the Middle East, Africa, and the Pacific Region) |