Pareto Charts
What is it?
A Pareto chart is a type of bar graph used to order categories based on their frequency. The most frequent being on the lefthand side and the least frequent on the right. What sets the Pareto chart apart from other bar graphs is the addition of the cumulative percentage axis and line.
Using a Pareto chart allows us to focus on where improvement efforts will make most impact.
The Pareto chart relates the pareto principle: roughly 80% of consequences come from 20% of causes (known as the “vital few”).
Why use it?
A Pareto chart can be a good way to identify which areas you should target to have the biggest impact. In the example to the left, wards 24L and 25L account for around 80% of falls. If you wanted to reduce falls across the site, you may want to focus your efforts on these wards in order to have the biggest impact.
How to use it?
Pareto charts can be made in Excel.
You need to start with your data as outlined on the right with your category on one side and the count on the other. From here, you need to highlight your data and click on “insert” from the toolbar. Locate the histogram icon as shown and select the option with the cumulative line. You should now have a Pareto chart.
To interpret your Pareto chart, it can be helpful to draw additional lines where the cumulative percentage line crosses the 80% mark, as shown below in blue. Where the blue and orange lines cross signifies your 80% or “vital few”.
More information
Our team has hosted a QI Spotlight session on Pareto charts, contact us here to access the recording
NES - Click here to see NES’ explanation of Pareto Charts
IHI - Click here for a different example of Pareto Charts