Pareto Chart
A pareto chart is a bar graph where the bars appear in decreasing length from left to right. The bar length corresponds to time, frequency, or amount.
When you want to find the most significant causes or problems from a larger known set of issues.
When examining the frequency of issues in a process.
1. DEVELOP A LIST of issues to be compared.
2. DEVELOP A STANDARD MEASURE of comparison for the issues.
3. DEFINE THE TIME PERIOD during which you will be collecting data.
4. TALLY, FOR EACH ITEM, HOW OFTEN IT OCCURRED (or cost or total time it took). Sum the amounts to find the overall total.
5. LIST THE ITEMS in descending order based on the unit you are measuring (most frequent to least frequent or greatest to least).
6. TO CONVEY CUMULATIVE DATA DRAW A LINE GRAPH for the cumulative percentages. The first point should line up with the top of the first bar.
7. ANALYZE THE DIAGRAM. Determine which items seem responsible for the majority of the issues or problems. This should be the point at which the graph quickly levels off.
Aids in action prioritization.
Shows the problems that appear to account for most of the variation.
Easy to construct with spreadsheet software.
Demonstrates which issues are the most significant or frequent.
May not have a standard measure for each item (i.e., cost, time, etc.).
University Research Co. LLC. Health care improvement project: pareto chart. 2008 [cited 2009 July 28];
George M, Rowlands D, Price M, et al. Identifying and verifying causes. The lean six sigma pocket toolbook. New York: McGraw - Hill; 2005. p. 141-96.
American Society for Quality. Cause analysis tools: pareto chart. 2009 [cited 2009 June 26]; Available from: http://www.asq.org/learn-about-quality/cause-analysis-tools/overview/pareto.html