A Pareto chart is a tool which is used to analyze
the relative frequency of deviations from specifications or success
criteria. The Pareto chart is a frequency histogramA bar graph that shows frequency of occurrence
versus value. Quite often the data is fitted to a distribution such
as a normal distribution. . which is ordered from
highest to lowest. Unlike control and capability charts, this chart
uses no statistical guides.

Pareto charts emphasize Pareto's empirical law
that any assortment of events consists of a few major and many
minor elements. In the context of SQC, it is important to select
the few vital major opportunities for improvement from the many
trivial minor ones. The Pareto chart is particularly useful for
Cost-to-fix versus Deviation-frequency analysis.

In addition to the histogram, typically a
cumulative percentage is also given. From top to bottom, the
percentage represents the ratio of the sum of evry value to this
point, to the sum of every value in the chart.