A vitality curve is a performance management practice that calls for individuals to be ranked or rated against their coworkers. It is also called stack ranking, forced ranking, and rank and yank. Pioneered by GE's Jack Welch in the 1980s, it has long been a controversial practice due to its negative effects on employee morale and potential for bias and discrimination. Many companies have abandoned the system in recent years, including GE and Microsoft. As organizational behavior expert David A. Thomas put it, "companies are playing their version of 'Survivor'".