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 fa st but relatively inaccurate measurement system that may be used to provide some initial information and a more accurate and expensive, and possibly s lower, alternative measurement device. In such circumstances, it is desirab le to determine the minimum cost-control chart for monitoring the productio n process using some combination of the measurement systems. This article d evelops such a procedure. An example of its use in the automotive industry is provided.