About the book
Control charts, also referred to as process-behavior charts, can be viewed as a statistical process control (SPC) tool intended to inform about the stability of a manufacturing or business process. Their initial conception is attributed to Walter A. Shewhart, physicist, engineer, and statistician mostly recognized for their pioneer role in quality control for the Bell Labs and Western Electric. An adequate sampling technique is critical for a powerful statistical evaluation. The control charts permit the control of processes over time, required rules for detecting signals of significant variation, such as the Western Electric rules, the Wheeler rules, and the Nelson rules in most of industry and business. However, some other specific fields adapted these rules, such as the Westgard rules for medical laboratory tests. There are several types of charts, usually for variables and attributes. The type selection is again critical for a consistent and reliable quality control methodology. So, the type of chart must fit the purpose of the control. Not only in-control and out-of-control signals must be detected. Trends and any other signal that is related to a risk of non-conforming performance are important to be recognized. Correction-action / preventive action should be implemented. Capability indexes, including sigma-metrics, are complementary to control charts. They express in an index the process stability. Close to the last 35 years that part of the industry and business quality control are based on a Lean-Six Sigma vision. Control charts have an important role in the successful practice of these models, including in the minimization of waste within a manufacturing process or process improvement.