A problem solving tool comprising a bar chart showing possible contributing factors in descending order; one of the Seven Quality Tools.
A Pareto chart, named after Vilfredo Pareto, is a type of chart which contains both bars and a line graph. The bars display the values in descending order, and the line graph shows the cumulative totals of each category, left to right.
The left vertical axis is the frequency of occurrence, but it can alternatively represent cost or other important unit of measure. The right vertical axis is the cumulative percentage of the total number of occurrences, total cost, or total of the particular unit of measure. Because the reasons are in decreasing order, the cumulative function is a concave function.
The purpose of the Pareto chart is to highlight the most important among a (typically large) set of factors. In quality control, it often represents the most common sources of defects, the highest occurring type of defect, or the most frequent reasons for customer complaints, and so on.
The Pareto chart is one of the seven basic tools of quality control. Others include the histogram, check sheet, control chart, cause-and-effect diagram, flowchart, and scatter diagram. These charts can be generated by many office (e.g., Microsoft Office, OpenOffice.org) and statistical software tools.