Pimwarat Nanthaprut. (2014) Improving of Test Statistic for the Risk Ratio in a Correlated 2 x 2 Table with Structural Zero. <i>Journal of SCIENCE and TECHNOLOGY Mahasarakham University</i>, <i>33</i>(2), 137-140.Pimwarat Nanthaprut. "Improving of Test Statistic for the Risk Ratio in a Correlated 2 x 2 Table with Structural Zero". Journal of SCIENCE and TECHNOLOGY Mahasarakham University 33 (2014):137-140.Pimwarat Nanthaprut. Improving of Test Statistic for the Risk Ratio in a Correlated 2 x 2 Table with Structural Zero. Mahasarakham University:ม.ป.ท. 2014.