Where it came from
After Pareto made his observation and created his formula, many others observed similar phenomena in their own areas of expertise. Quality Management pioneer, Dr. Joseph Juran, working in the United States in the 1930s and 1940s recognized a universal principle he called the "vital few and trivial many" and reduced it to writing in his Quality Control Handbook. In an early work, a lack of precision on Juran's part made it appear that he was applying Pareto's observations about economics to a broader body of work. The name Pareto's Principal stuck, probably because it sounded better than Juran's Principle. As a result, Dr. Juran's observation of the "vital few and trivial many", the principle that 20 percent of something always are responsible for 80 percent of the results, became known as Pareto's Principle or the 80/20 Rule.