Statistical Process Control Using Two Measurement Systems

Often in industry critical quality characteristics can be measured by more than one measurement system. Typically, in such a situation, there is a fast but relatively inaccurate measurement system that may be used to provide some initial information, and a more accurate and expensive, and possibly slower, alternative measurement device. In such circumstances, it is desirable to determine the minimum cost control chart for monitoring the production process using some combination of the measurement systems. This article develops such a procedure. An example of its use in the automotive industry is provided.