A pareto graph is graph that is specifically designed for identifying sources of defects. In a pareto graph, a series of bars identifies different sources of defects. They are arranged by value, from the greatest number to the lowest number. A line shows the percentage of the cumulative values of the bars, to the total values of all the bars in the graph. The line always ends at 100 percent.
Pareto graphs are dual-Y graphs. The Y1-axis corresponds to values that the bars represent. The Y2-axis corresponds to the cumulative percentage values.
You use pareto graphs to identify types and sources of defects, so that you can focus corrective action on the biggest sources of problems.
Only one variety of pareto graph is available. The constant is PARETO
.
The following properties of the Graph
object affect pareto graphs:
ParetoBarsConnected
-- Specifies whether the bars touch either
other.
DepthRadius
and DepthAngle
-- Together, these
properties specify whether the graph appears to have depth.
The following figure shows the data structure of a pareto graph. In this graph, each of five bars shows a cause of a traffic fatality. The first two causes, failure to maintain lane and high speed, account for 70 percent of the total fatalities.
The data structure for bar graphs is as follows:
A group is represented by a bar. Sort group values by value, descending. A group is labeled by an X tick label, such as Lane.
A series is represented by bars of the same color. Only one series appears in a pareto graph. Because only one series appears in a pareto graph, the legend does not appear, and no graph component labels the series. The previous figure shows the series infromation in the graph title.
The line in a pareto graph is calculated from the data values that you supply to the graph.
Pareto graph data has the following guidelines:
Graphs display numeric data only.
Pareto graphs require at least two groups of data. If you pass only one column of data, then the Graph bean displays a message about insufficient data, instead of displaying a graph.
Pareto graphs cannot have negative numbers. If you pass negative numbers
to a pareto graph, then the graph sends an AlertEvent
to any
AlertListeners
that have been registered. The ID of the alert
event is either DATA_ALL_DATA_NULL_NEG_ZERO
or DATA_PARTIAL_DATA_NULL_NEG_ZERO
.
Only the first series of data appears in a pareto graph.
Groups should be sorted by value, from the highest value to the lowest value. The graph does not sort the groups by value.
Do not pass percentage values as part of the data. The graph calculates the percentages, based on the data that you pass.