The 80:20 rule aka Pareto Principle

A statistical rule of thumb that states 80% of results often come from approximately 20% of causes. This relationship identified in 1895 by Italian economist Vilfredo Pareto who discovered that 20% of Italy’s citizens owned 80% of the country’s wealth. 

•Examples:

•80% of sales result from 20% of clients.

•80% of new clients from referrals from 20% of existing clients

•80% of the effects originate from 20% of the causes

•80% of problems come from 20% of processes