A model is introduced for measurements obtained in collaborative interlaboratory studies, comprising measurement errors and random laboratory effects that have Laplace distributions, possibly with heterogeneous, laboratory-specific variances. Estimators are suggested for the common median and for its uncertainty, as well as confidence intervals. We provide predictors of the laboratory effects, and of their pairwise differences, along with the corresponding uncertainties. Explicit formulas are given for these estimators, and their sampling performance is assessed in a Monte Carlo simulation study.
Pub Type: Journals
bayes estimators, degrees of equivalence, heteroscedasticity, laplace distribution, maximum likelihood estimation, meta-analysis, random effects model, interlaboratory study, key comparisons.