what is the 80 20 rule 
the 80 20 rule also known as the pareto principle is a familiar saying that asserts that 80 of outcomes or outputs result from 20 of all causes or inputs for any given event in business a goal of the 80 20 rule is to identify inputs that are potentially the most productive and make them the priority for instance once managers identify factors that are critical to their company s success they should give those factors the most focus although the 80 20 rule is frequently used in business and economics you can apply the concept to any field wealth distribution personal finance spending habits and even infidelity in personal relationships can all be the subject of the 80 20 rule investopedia jessica olah