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Mark Vangel Presentation Abstracts |
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The Analysis of Interlaboratory Study Data
Mark Vangel |
| Abstract | Arriving at a consensus by combining information is a common problem in applied statistics. We consider aspects of this problem relevant to collaborative (or `interlaboratory') studies, which are particularly common in analytical chemistry and engineering. Two situations will be discussed. For the simpler case, measurements are made on a single material by multiple laboratories. The laboratories may differ in the precision with which they make the measurements, as well as in the number of measurements made. A one-way random normal ANOVA model is assumed: unbalanced and with unequal within-group variances. For the second situation, each laboratory makes measurements on m materials, so a two-way normal mixed model is used, again with lack of balance and unequal within-laboratory variances. For both the one- and two-way cases, we are interested in consensus estimates of material means, estimates of between-laboratory variability, and uncertainties in these estimates. A review of some approaches in common use will be followed by new results for maximum-likelihood and Bayesian analyses, illustrated with examples. |
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Date created: 8/28/2001 |
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