Pareto analysis


Pareto analysis is based on the observation that the majority of a product’s defects (80%) arise from a small number of causes (20%).

Also known as

  • Pareto principle.
  • 80/20 principle.

The tool

The 80/20 principle is a generalisation, rather than a hard and fast rule.

Knowing where the most common problems arise allows analysts to:

  • Address these problems (as part of Cause and Effect analysis)
  • Speed up rates of repair, by having repairers look for and fix or rule out the most obvious problems first.

In order for meaningful conclusions to be drawn, Pareto analysis requires a comprehensive set of categories and a large dataset. The use of a small number of categories or observations may lead to inaccurate conclusions.

The model does not recognise that minor problems may escalate over time to become major issues.

Patterns can be identified by using a Pareto Chart (see diagram [KS – need diagram]).

Why use it

  • Pareto analysis can be used as part of, or in conjunction with, cause and effect analysis (aka Root Cause Analysis), to highlight the most important among a set of a factors which cause problems.
  • Pareto analysis enables users to identify precise patterns and proportions by measuring and charting numbers and frequencies of different types of faults.

When to use it

How to use it



Similar to

Use in conjunction with

Complemented by


Additional information