Pareto's Principle Aka 80/20 Rule
A high percentage of effects in any large system are caused by a low percentage of variables.
In other words there is a small subset of inputs that are responsible for the majority of the outputs.
The 80/20 rule asserts that approximately 80 percent of the effects generated by any large system are caused by 20 percent of the variables in that system. The 80/20 rule is observed in all large systems, including those in economics, management, user interface design, quality control, and engineering, to name a few. The specific percentages are not important, as measures of actual systems indicate that the proportion of critical variables varies between 10 percent and 30 percent. The universality of the 80/20 rule suggests a link to normally distributed systems, which limits its application to variables that are influenced by many small and unrelated effects—e.g., systems that are used by large numbers of people in a variety of ways. - Universal Principles of Design
Examples:
- 80 percent of a product’s usage involves 20 percent of its features.
- 80 percent of a town’s traffic is on 20 percent of its roads.
- 80 percent of a company’s revenue comes from 20 percent of its products.
- 80 percent of innovation comes from 20 percent of the people.
- 80 percent of progress comes from 20 percent of the effort.
- 80 percent of errors are caused by 20 percent of the components.
Notes
The 80/20 rule is useful for focusing resources and, in turn, realizing greater efficiencies in design. For example, if the critical 20 percent of a product’s features are used 80 percent of the time, design and testing resources should focus primarily on those features. The remaining 80 percent of the features should be reevaluated to verify their value in the design. Similarly, when redesigning systems to make them more efficient, focusing on aspects of the system beyond the critical 20 percent quickly yields diminishing returns; improvements beyond the critical 20 percent will result in less substantial gains that are often offset by the introduction of errors or new problems into the system.
All elements in a design are not created equal. Use the 80/20 rule to assess the value of elements, target areas of redesign and optimization, and focus resources in an efficient manner. Noncritical functions that are part of the less-important 80 percent should be minimized or removed altogether from the design. When time and resources are limited, resist efforts to correct and optimize designs beyond the critical 20 percent, as such efforts yield diminishing returns. Generally, limit the application of the 80/20 rule to variables in a system that are influenced by many small and unrelated effects.
References
- Universal Principles of Design (pg. 14)
Backlinks