作者：SCHOENFELD, DA; TSIATIS, AA
作者单位：Harvard University; Harvard Medical School; Harvard University Medical Affiliates; Dana-Farber Cancer Institute
摘要：Clinical trials often employ a stratified randomization so that treatment arms are balanced within prognostic factors. In these circumstances the use of the ordinary log rank test for comparing treatment groups with respect to survival is invalid. The stratified log rank test, although valid, loses efficiency as the number of strata increases. This paper proposes a modified log rank test that is fully efficient when there is no strata effect and is more efficient than the stratified log rank t...
作者：FLURY, BK
摘要：Under the common principal component model the covariance matrices .PSI.i of k populations are assumed to have identical eigenvectors, that is, the same orthogonal matrix diagonalizes all .PSI.i simultaneously. This paper modifies the common principal component model by assuming that only q out of p eigenvectors are common to all .PSI.i, while the remaining p - q eigenvectors are specific in each group. This is called a partial common principal component model. A related modification assumes t...
