On two approximations to the F-distribution: Application to testing for intraclass correlation in family studies

Two approximations to the F-distribution are evaluated in the context of testing for intraclass correlation in the analysis of family data. The evaluation is based on a computation of empirical significance levels and a comparison between p-values associated with these approximations and the corresponding exact p-values. It is found that the approximate methods may give very unsatisfactory results, and exact methods are therefore recommended for general use. Dans le contexte de tests pour la correlation intra-classe, utiles pour l'analyse de donnees relatives aux familles, on evalue deux approximations de la loi F. L'evaluation est basee sur le calcul de seuils empiriques et sur la comparaison entre les probabilites de depassement exactes et celles associees aux approximations. On trouve que les methodes approximatives peuvent conduire a des resultats tres insatisfaisants et que, par consequent, les methodes exactes sont recommandees.