Test regions using two or more correlated product characteristics

For inspection of manufactured parts, it may be much easier and/or cheaper to use the information from two or more product characteristics which are strongly related to the characteristic of interest, than to measure this characteristic itself. To get high quality output, it is required that from the accepted parts only a given, typically very small, fraction is nonconforming. In this paper test regions are determined such that, under the preceding condition, the number of accepted products is maximized. The good performance of the methods is illustrated by Monte Carlo results. An application in semiconductor industry shows its value in practice.