Pareto chart

A Pareto chart is a bar chart, in which the individual values ​​of the quantity to be reproduced after sorted. In this case, the largest value is the smallest value is far left, far right of the chart. The Pareto diagram is named after the Italian economist Vilfredo Pareto. It finds use inter alia in the statistics.

Definition

The Pareto chart is based on the Pareto principle, according to which most of the effects of a problem (80 %) are often attributed only to a small number of causes ( 20%). There is a bar chart that ranks causes of problems in order of importance. See also the article on the Pareto distribution - limiting the sources of errors / rapid determination of decision aids.

Purpose

With the help of Paretodiagramms be out of many possible causes of a problem those filtered out that have the greatest impact. The importance of a cause can be read directly from the diagram.

For example, if the company would thus successfully take care of the first three reasons for lateness at work, they would have about 80 % of cases solved ( see diagram).

See also ABC analysis, XYZ analysis, ABC / XYZ analysis.

Procedure

First, the topic to be processed is fixed. Then categories are formed, for example, for types of error or causes or for products, customers, products, suppliers.

In addition, a size must be determined by which one can clarify the effects of the problem. The most common sizes are the frequency of occurrence, or valued at cost incidence (number multiplied by expense ratio), or the likelihood and impact, or in the FMEA, the occurrence probability and the probability Discover the cause and significance of the error sequence.

To create the Pareto diagram is determined from the absolute frequency ( or the related measure ) each error category, their percentage:

The categories are sorted in descending order according to their importance and then plotted on the horizontal axis from left to right. About each error category, a column is drawn whose height corresponds to the frequency of occurrence. The columns are stacked on one another from left to right, the result is the Pareto curve on the accumulated percentage value can be read.