by | Jul 26, 2017 | Uncategorized | 0 comments

In large systems, a high percentage of effects come from a low percentage of causes.
Also known as the Pareto Principle, and the Law of Vital Few and Trivial Many, this rule declares that the majority (70-90%) of effects in a large system are caused by a minority (10-30%) of variables in that system. This rule can be applied to a range of systems including economics, engineering, design, project management and quality control.
Examples of the 80/20 rule include:
  • 80% of errors are caused by 20% of code
  • 80% of revenue comes from 20% of customers
  • 80% of time is spent using 20% of a product’s features
  • 80% of wealth in Italy is owned by 20% of the population
  • 80% of website traffic occurs during 20% of the time
In design and development the rule can be useful in focusing resources. For example, if users of a product utilise 20% of its functions 80% of the time, design and testing time should be concentrated on the 20% of features most-used. Functions which fall in the less-used 80% could be hidden from the interface or removed from the system entirely.