Test limits in quality control using correlated product characteristics

To guarantee the quality of a product, in quite a few production processes all produced items are inspected before they go to the consumer. In case there is one product characteristic that has to conform a certain specification limit, inspection can take place by measuring this characteristic and comparing it to a test limit. This test limit is in general slightly more strict than the specification limit, because of a measurement error in measuring the characteristic. Instead of measuring the characteristic itself, one can also inspect an item by means of the measurements of other characteristics that are related to the characteristic of interest. This may be of interest if it is very costly to measure the characteristic itself, or if the characteristic itself can only be measured destructively. In this thesis we show how the measurements of these correlated characteristics can be used to inspect the characteristic of interest.