80/20 Rule
This is a rule of thumb that says that 80% of the problems happen in 20% of
the problem domain. In fact many things seem to naturally fall into these
categories (which is probably something to do with Murphy's Law
:). It was originally
identified by 19th century Italian economist, Vilfredo Pareto, who noticed that around 80%
of the wealth of the country was held by around 20% of the population (and that this was
recursive: of the 20%, 80% of their wealth was held by 20% of this privileged
society).
Joseph Juran called it the Pareto Principle and applied it
to process improvement as a simple tool for focusing activity.
See also:
Joseph Juran, Pareto
Principle, Pareto Chart
Toolbook chapter:
Pareto Chart
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