The Pareto principle states that 80% of the impact of the problem will show up in 20% of the causes. (Originally stated: 80% of the wealth is owned by 20% of the people.) A bar chart that displays by frequency, in descending order, the most important defects. Proper use of this chart will have the cumulative percentage on a second y-axis (to the right of the chart). This chart-type is used to identify if the Pareto principle is evident in the data. If the Pareto principle is evident, about 20% of the categories on the far left will have about 80% of the impact on the problem.