Use and interpretation of statistical quality control charts.

Originally developed at Bell Laboratories by Dr Walter Shewhart [1] in 1924 specifically to help detect statistical changes in process quality, control charts have since become one of several primary tools of quality control and process improvement. Quality control charts are chronological graphs of process data that, although based in statistical theory, are easy for practitioners to use and interpret. These charts also can help users to develop an understanding of the performance of a process and to evaluate any benefits or consequences of process interventions, complementing traditional methods by providing additional longitudinal information that otherwise might not be detected [2]. This article provides a brief introduction to the use of statistical quality control charts for analyzing, monitoring, and improving health care processes. After an overview of key concepts, several examples illustrate control chart use and interpretation. The article concludes with some common pitfalls to avoid and references for further exploration. Readers unfamiliar with the topic should also read introductory materials on the principles of quality management and the philosophies of the late quality pioneer, Dr W. E. Deming [3].