توان آزمون پارامتر شكنندگي مشترك در آناليز بقا و كاربرد آن در زمان بقاي پيوند قرنيه دو چشم

The Shared Frailty Parameter due to unobserved genetic and environmental factors implies positive correlation among the failure times of individuals of the same groups. To estimate this parameter some studies have been conducted. The object of this study is determination of power and sample size for testing this parameter and evaluating the power of the test based on corneal transplant failure times. This is possible through linear models of maximum likelihood estimators but depends on the norm of a bounded function. In this study by using asymptotic distribution of maximum likelihood estimator which is a mixture of a normal distribution and a mass point on zero and estimating its variance by inversing the observed information matrix, the power of the test is estimated, in this case the power depends on sample size and the sample size can be determined by iterative methods to achieve the required power.