The left vertical axis is the frequency of occurrence, but it can alternatively represent cost or another important unit of measure.

To take the example below, in order to lower the amount of late arrivals by 78%, it is sufficient to solve the first three issues.

The purpose of the Pareto chart is to highlight the most important among a (typically large) set of factors.

In quality control, Pareto charts are useful to find the defects to prioritize in order to observe the greatest overall improvement.

Wilkinson (2006) devised an algorithm for producing statistically based acceptance limits (similar to confidence intervals) for each bar in the Pareto chart.