The Bell Curve (also called the normal distribution curve’) had been the standard for assessing and categorising employees performance at corporations the world over for the lasr 50 years. The Bell Curve is used to analyse employee performance, and its bell-shape forces the majority of employees to be ranked as ‘average’ (at or near the mean of the curve),while only a small number are ranked as either ‘high’ or ‘low’ performers.
To fit all employees in this bell-shaped garding system, the number of high-achievers has to be equivalent to the number of underperforming individuals; this implies that there will always be ‘losers’, even if your team Comprises highly productive employees for the most part.
Recent research conducted in 2011 and 2012 by organizational psychologists Ernest O.Boyle Jr. and Herman Aguinis challenges the Bell Curve method, and has reveled that it is not an accurate measure of work performance because it forces manager to ‘fit’ people in the curve, which proves to be detrimental to individual, team and company morale.
Consequently, line managers are opting for ‘Power Law’ (also called the Paretian Distribution) to conduct performance appraisals. The Power Law categorises performance in three ranks: a small number of people fall in the ‘hyper high-performers’ group, a broad range of people are termed ‘good performers’, and a small number of people are ‘low-performers’, prevalent in the Bell Curve method, meaningless. More importantly, supervisors do not have to put people in any category; employee rankings depend entirely on the levels and quality of work output.
Using the Bell Curve to assess employee is therefore now becoming obsolete; research and practical experience shows it to be counterproductive, since someone will always have to fill the gap at the lowest end of the curve. The power law on the other hand, encourages everyone to move up the ranks to become a hyper high-performer, rather than limiting the number of employees who can reach the top.
By Fuzia Kerai Khan. The writer is Chief Consultant, i&b Consulting, Training, e-learning.