The Economic Design of Control Charts: A Unified Approach

The choice of control chart parameters—sample size, sampling interval, and control limits—is considered from an economic point of view. A general process model is considered, and the hourly cost function is derived. This cost function simplifies when the recorded statistics are independent. Numerical techniques to minimize this cost function are discussed, and sensitivity analyses are performed. An example illustrates the potential savings of this technique of designing control charts.