p expected proportion of nonconforming items produced by the process The lower and upper control limits, LCL and UCL, respectively, are computed as A lower probability limit for p i can be determined ...

A control chart consists of several parts ... the control plan direction for a UCL special cause. Use the UCL (Along with the LCL) to Evaluate the Predicted Spread of Common Cause Variation ...

This assumes that the process is in statistical control and that X i is binomially distributed. The lower probability limit LCL is then calculated by setting and solving for LCL. Similarly, the upper ...