NONPARAMETRIC TESTS FOR BIASED COIN DESIGNS (RANDOMIZATION)
Consider a clinical trial where treatments A and B are assigned to n patients via Efron's (1971) biased coin design. Randomization tests of the null hypothesis H(,0) of no treatment difference are studied. We derive a recursion procedure for obtaining the exact randomization distribution for each member of a class of test statistics. This enables one to perform exact tests of H(,0). In accordance with Cox' (1982) suggestion, the randomization distributions of the test statistics are conditional on the terminal imbalance of the treatment allocation. Letting T(,1), ..., T(,n) be the treatment assignment variables, with T(,i) = 1 if the i('th) patient receives treatment B, = 0 if the i('th) patient receives treatment A, conditional distributional properties of these variables are obtained. Recursive procedures for computing the conditional exact and approximate moments of T(,1), ..., T(,n) are also derived. Based on these results, test statistics are proposed for use in the randomization tests when the sample size is large. The adequacy of the normal approximations to the conditional randomization distributions of these statistics are ascertained via a computer simulation.
|Authors:||PENA, EDSEL ALDEA|
Florida State University Libraries
|Type of publication:||Other|