A Pareto diagram is a special type of bar chart that is used to separate the “vital few” from the “trivial many.” It is based on the 80/20 rule; e.g., 20% of our customers buy 80% of our products. The horizontal (x) axis most often represents problems or causes of problems (the “categories”). The vertical (y) axis most often represents frequency or cost (the “frequencies”). The problem or cause that occurs most frequently (or costs the most) is listed first on the x axis. The second most frequently occurring problem or cause is listed second and so on. A bar is generated for each cause or problem. The height of the bar is the frequency with which that problem or cause occurred. A cumulative percentage line is sometimes added to the Pareto diagram.
Types of Pareto Diagrams
There are three options for Pareto diagrams in the SPC for Excel program. Select the link for details on how to create each type of Pareto diagram using SPC for Excel.