Simultaneous estimation and reduction of nonconformity in interlaboratory studies

Several procedures that are designed to reduce nonconformity in interlaboratory studies by shrinking data towards a consensus weighted mean are suggested. Some of them are shown to have a smaller quadratic risk than the vector sample means. Shrinkage towards a weighted mean in a random-effects model and a statistic appearing in models which allow for systematic errors are also considered. The results are illustrated by two examples of collaborative studies. Copyright Journal compilation (c) 2010 Royal Statistical Society. No claim to original US Government works.