Power-law distribution usurps bell curve.

• Position: Performance Measures - Employee performance

The dreaded bell curve that has haunted generations of students with seemingly preordained grades also has migrated into business as the standard for assessing employee performance, but it now turns out--revealed in a study by Indiana University, Bloomington--that individual performance unfolds not on a bell curve, but on a "power-law" distribution, with a few elite performers driving most output and an equally small group tied to damaging unethical or criminal activity.

This turns on its head nearly a half-century of plotting performance evaluations on a bell curve, or "normal distribution,"' in which equal numbers of people fall on either side of the mean. Researchers predict that the findings could force a wholesale reevaluation of every facet related to recruitment, retention, and performance of individual workers, from pre-employment testing to leadership development.

"How organizations hire, maintain, and assess their workforce has been built on the idea of normality in performance, which we now know is, in many cases, a complete myth," explains study author Herman Aguinis, professor of organizational behavior and human resources. "lf, as our results suggest, a small, elite group is responsible for most of a company's output and success, then it's...