The empirical likelihood approach is suggested to the pretest-posttest trial based on the constrains,which we construct to summarize all the given information.The author obtains a log-empirical likelihood ratio test statistic that has a standard chi-squared limiting distribution.Thus,in making inferences,there is no need to estimate variance explicitly,and inferential procedures are easier to implement.Simulation results show that the approach of this paper is more efficient compared with ANCOVA Ⅱ due to the sufficient and appropriate use of information.
This paper discusses the nested case-control analysis under a class of general additive-multiplicative hazard models which includes the Cox model and the additive hazard model as special cases.A pseudo-score is constructed to estimate the regression parameters.The resulting estimator is shown to be consistent and asymptotically normally distributed.The limiting variance-covariance matrix can be consistently estimated by the nested case-control data.A simulation study is conducted to assess the finite sample performance of the proposed estimator and a real example is provided for illustration.
The case-cohort design is widely used in large epidemiological studies and prevention trials for cost reduction.In such a design,covariates are assembled only for a subcohort which is a random subset of the entire cohort and any additional cases outside the subcohort.In this paper,we discuss the case-cohort analysis with a class of general additive-multiplicative hazard models which includes the commonly used Cox model and additive hazard model as special cases.Two sampling schemes for the subcohort,Bernoulli sampling with arbitrary selection probabilities and stratified simple random sampling with fixed subcohort sizes,are discussed.In each setting,an estimating function is constructed to estimate the regression parameters.The resulting estimator is shown to be consistent and asymptotically normally distributed.The limiting variance-covariance matrix can be consistently estimated by the case-cohort data.A simulation study is conducted to assess the finite sample performances of the proposed method and a real example is provided.
