Process Behavior Chart

A term popularized by Donald Wheeler to better describe control charts. He focuses on observing and understanding the data, and feels that the word “control” is misleading.

Traditional statistical process control (SPC) charts assume a normal distribution of the data, process behavior charts have less assumptions about normality. These charts don’t utilize as many rules to detect out of control conditions (looking for data outside of 3-sigma limits primarily, not all of the Nelson Rules).

He feels PBC strikes a balance between the economic consequences of two mistakes (reacting to noise and failing to detect a signal) by filtering out the noise to reveal the true signals.

It also uses different terminology such as signal vs noise, instead of common vs special cause variation used in SPC.

Despite the slight differences, both methods use Individuals and Moving Range (I-mR) charts to plot the data.

Learn more about PBC’s at https://www.leansixsigmadefinition.com/summary-of-donald-wheelers-understanding-statistical-process-control-uspc-seminar/