P chart properties |
Configuring a P chart |
P chart calculations

The P chart is an attribute control chart that shows the
proportion of nonconforming units from samples of varying/constant
size. Proportion is defined as the ratio of nonconforming items in
a population to the total number of items in a population. The
process attribute is described as one of two possible outcomes, for
example, pass/fail, yes/no, and so forth.

In the following P chart example, the x-axis shows the
percentage of nonconforming items for each sample. In this case,
the constant sample size is set by the data source. The control
limits (shown on the chart as UCL, CL, LCL, WL1, and WL2) are also
set according to the data and a sigma limit of 3.

### See Also