Search

In manufacturing, we often use a binary measurement system (BMS) for 100% inspection to protect customers from receiving nonconforming product. We can assess the performance of a BMS by estimating the consumer's and producer's risks, the two misclassification rates. Here, we consider assessment plans and their analysis when a gold standard system (GSS) is available for the assessment study but is too expensive for everyday use. We propose a random-effects model to allow for variation in the misclassification rates within the populations of conforming and nonconforming parts. One possibility, here denoted the standard plan, is to randomly sample n parts and measure them once with the GSS and r times with the inspection system. We provide a simple analysis and planning advice for standard plans. In practice, the misclassification rates are often low and the underlying process has high capability. This combination of conditions makes the assessment of the BMS challenging. We show that we need a very large nu...

Binary measurement systems that classify parts as pass or fail are widely used in industry, especially for systematic inspection in high-volume processes. In this context, we are likely to have available a large number of previously measured passed and failed parts. To support production and quality improvement, it is important to assess the misclassification rates, e.g., the probability of failing a conforming part or passing a nonconforming part. We may also want to estimate the unknown conforming rate. Here we focus on the assessment of a binary measurement system when no gold-standard measurement system is available. The standard assessment plan is to repeatedly measure a sample of parts and use a latent class model. We demonstrate the substantial benefit of supplementing the standard plan with the available data from the previously measured parts. We propose new sampling plans and compare them with the standard plan with respect to the precision of the estimators of the misclassification rates. We also give recommendations for planning an assessment study when we can sample from a population of previously measured parts.

Despite the widespread use of binary measurement systems, little has been written about assessing them. Two plans are proposed here for assessing binary measurement systems that may be used under the assumption that the pass rate of the system is known..

This research was supported by grants from the Natural Sciences and Engineering Research Council of Canada.