协变量的不均衡对协方差分析的影响

目的探讨协变量的不均衡对协方差分析的影响。方法通过MonteCarlo模拟并结合临床试验实例对作协方差分析时引入不均衡的协变量来校正的前后变化作比较。结果协变量的不均衡对协方差分析的检验效能是存在一定影响的,无论协变量不均衡程度有多大,在作协方差分析时引入不均衡的协变量来校正总是有一定代价的。结论新药临床试验中常常存在病人的基线特征在处理组间不均衡从而影响对试验结果的正确评价。可以在作协方差分析时引入该不均衡的协变量去处理,但要根据协变量的不均衡程度及试验目的等实际情况加以权衡。

Effect of Covariate Imbalance on the Power of ANCOVA

ObjectiveTo study the effect of covariate imbalance on analysis of covariance.MethodsTo compare the power of corrected ANCOVA with imbalanced covariates and the power of uncorrected ANCOVA.ResultsCovariate imbalance affects the power of ANCOVA.Regardless of covariate imbalance's degree,there is always some cost to correct ANCOVA with imbalanced covariates.ConclusionIn clinical trials,patients'baseline imbalance among groups always affect the evaluation to trials'outcome.We can do ANCOVA corrected by imbalanced covariates,depending on covariate imbalance's degree and objective of the trial and so on.