USING CONFIDENCE-INTERVALS TO TEST VARIANCE-COMPONENTS

Tests of hypotheses for variance components are often of interest in r andom effects analysis of variance models. However, in many applicatio ns, exact tests are not available and approximate methods must be used . Many investigators form approximate tests based on ''quasi'' F ratio s. A different approach based on a confidence interval for the varianc e component is proposed in this paper. The approach is illustrated wit h a random effects three-factor crossed design, and guidelines are pro vided for application to other designs.