Pareto Chart

The Pareto chart, or Pareto diagram, is one of the seven basic tools of quality improvement. It is named after the Italian economist Vilfredo Pareto (1848–1923), who observed that a small minority of Italian citizens held the majority of the wealth and means of production. His studies led him to conclude that 20% of the people in Italy owned 80% of the wealth. Quality expert Dr. Joseph M. Juran applied the “Pareto principle” to industry, and to specific processes within industry, noting that whenever a number of individual factors contribute to some overall effect, relatively few of those items account for the bulk of that effect.

Figure 1 Pareto Chart

Using the Pareto principle has proven an effective technique in the health services sector. The principle reinforces the practical reality that, given limited resources, efforts must be concentrated on issues that have the most potential impact. A Pareto analysis can assist a quality improvement team in setting priorities on its actions and also helps the team define and focus the problem.

The Pareto chart is graphically depicted as a bar chart, with each bar representing a separate problem cause. In the chart, the bars are ordered from left to right according to height, which signifies frequency. Thus the tallest bar, the most frequently occurring factor, is on the far left. Often included in the Pareto chart is a line graph that shows the cumulative percentage for all the categories of problem causes. Throughout the quality improvement process, the Pareto chart serves as a useful tool for identifying those factors that may produce the greatest effect in quality improvement.

A hypothetical example of the Pareto principle follows. Hospital A is focusing its quality improvement efforts on eliminating sources of outpatient dissatisfaction. An analysis of its most recent outpatient satisfaction survey reveals that all the sources of patient dissatisfaction fall into one of 10 survey questions. Each survey question represents a distinctive issue or category of dissatisfaction, such as long wait for an appointment, lack [Page 416]of courtesy on the part of support personnel, and perceived lack of provider competence. The Pareto chart depicted in Figure 1 indicates that, from these 10 categories three (30%) account for 70% of the patient dissatisfaction. Thus from a purely practical perspective, the quality improvement team would initially focus its efforts on those three patient complaint categories. In a Pareto analysis, this is referred to as distinguishing “the vital few” from “the trivial many.”