Journal of Biometrics & Biostatistics

Yasutaka Chiba

Publications

• Research Article
  Exact Tests for the Weak Causal Null Hypothesis on a Binary Out come in Randomized Trials
  Author(s): Yasutaka ChibaYasutaka Chiba
  
  There are two principal exact tests for evaluation of data in two-by-two contingency tables: the tests of Fisher and Barnard. The latter cannot be a hypothesis test for the causal null hypothesis unless exchangeability can be assumed. Fisher’s exact test is a hypothesis test for the sharp causal null hypothesis (i.e., that there is no effect for all individuals), but not for the weak causal null hypothesis (i.e., that the true risk difference is zero). Rejection of the sharp causal null hypothesis does not mean that the weak causal null hypothesis is rejected (i.e., that the true risk difference is not zero). In this article, we provide exact tests for the weak causal null hypothesis, in the absence of any assumption, in the context of randomized trials. Using the concept of principal stratification, which considers four types of subjects to define four principal strata, we deri.. Read More»
  DOI: 10.4172/2155-6180.1000244

  Abstract PDF