Pareto charts are used to analyze the root cause of process defects. They are based on the “Pareto Principal” which claims that 80% of the defects are caused by only 20% of the defect categories.
Pareto charts resemble bar charts but are different. In a Pareto chart, the defect category with the largest number of defects always appears as the first and tallest bar on the chart. The other bars represent the remaining defect categories in descending order of magnitude.