Accurate Unconditional P-values For A Two-arm Study With Binary Endpoints
Journal of Statistical Computation and Simulation
Taylor and Francis Ltd.
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Unconditional exact tests are increasingly used in practice for categorical data to increase the power of a study and to make the data analysis approach being consistent with the study design. In a two-arm study with a binary endpoint, p-value based on the exact unconditional Barnard test is computed by maximizing the tail probability over a nuisance parameter with a range from 0 to 1. The traditional grid search method is able to find an approximate maximum with a partition of the parameter space, but it is not accurate and this approach becomes computationally intensive for a study beyond two groups. We propose using a polynomial method to rewrite the tail probability as a polynomial. The solutions from the derivative of the polynomial contain the solution for the global maximum of the tail probability. We use an example from a double-blind randomized Phase II cancer clinical trial to illustrate the application of the proposed polynomial method to achieve an accurate p-value. We also compare the performance of the proposed method and the traditional grid search method under various conditions. We would recommend using this new polynomial method in computing accurate exact unconditional p-values. © 2018 Informa UK Limited, trading as Taylor & Francis Group.
Global maximum; grid search; independent proportions; polynomial; unconditional tests
Accurate Unconditional P-values For A Two-arm Study With Binary Endpoints.
Journal of Statistical Computation and Simulation, 88(6),
Taylor and Francis Ltd..