A Pareto diagram is used to determine what characteristic is the major contributor in a process. The diagram is constructed by ranking the data in frequency of occurrence and plotting the bars in descending order. 

An example of a Pareto Diagram and how to create it in SPC XL is shown below.

• A computer manufacturer has maintained records of why people return computers. A subset of the data is shown below.

• In SPC XL, select "SPC XL" - "Analysis Diagrams" - "Pareto Chart..." from Excel's menu bar.

• The first step is to select the source data for the Pareto Chart.

• The second step is to choose the options for the Pareto. You can change the sort order, bar type, gap width (the distance between bars), and the # of groups.

• Finally, enter the desired chart and axis titles.

• SPC XL creates the Pareto Chart.

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