There is a long standing belief in business that people performance follows the Bell Curve (also called the Normal Distribution). This belief has been embedded in many business practices: performance appraisals, compensation models, and even how we get graded in school. (Remember "grading by the curve?")
Research shows that this statistical model, while easy to understand, does not accurately reflect the way people perform. As a result, HR departments and business leaders inadvertently create agonizing problems with employee performance and happiness.
Via Vicki Kossoff @ The Learning Factor