A conservative test and confidence region for comparing heteroscedastic regressions

Abstract

The problem of comparing two regression planes without the assumption of equal variances is considered. A natural analogue of the Behrens-Fisher statistic is proposed and its distribution bounded in terms of the studentized maximum and minimum chi-squared distributions. The results are used to construct conservative tests and confidence regions for comparing the regression parameters. Numerical comparisons with more specialized bounds due to Hsu (1938), Hájek (1962) and others are made.