Vitality curve
（重定向自Rank and yank）
A vitality curve is a leadership construct whereby a workforce is graded in accordance with the individual productivity of its members. It is also known as forced ranking, forced distribution, rank and yank, quota-based differentiation, and stack ranking.
The often cited "80-20 rule" — also known as the "Pareto principle" or the "Law of the Vital Few" — whereby 80% of crimes are committed by 20% of criminals, or 80% of useful research results are produced by 20% of the academics, is an example of such forced rankings. In some cases such "80-20" tendencies do emerge, and a Pareto distribution curve is a fuller representation.