The Pareto Principle (The 80/20 Rule)

The Law

Most things in life are not distributed. In some cases, the majority of results come from a minority of inputs.

This principle is known as:

• The Pareto Principle
• The Law of the Vital Few
• The Principle of Factor Sparsity

Examples

In 2002 Microsoft reported that by fixing the top 20% of the most-reported bugs, 80% of the related errors and crashes in windows and office would become eliminated (Reference).

• 80% of a certain piece of software can be written in 20% of the total allocated time.
• 20% of the code takes 80% of the time.
• 20% of the effort produces 80% of the result.
• 20% of the work creates 80% of the revenue.
• 20% of the bugs cause 80% of the crashes.
• 20% of the features cause 80% of the usage.