Program on Causal Inference, Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts 02116, USA.
Am J Epidemiol. 2012 Sep 15;176(6):555-61. doi: 10.1093/aje/kws131. Epub 2012 Aug 28.
Consider a study in which the effect of a binary exposure on an outcome operates partly through a binary mediator but measurement of the mediator is nondifferentially misclassified. Suppose that an investigator wishes to estimate the direct and indirect effects of the exposure on the outcome. In this paper, the authors describe a mathematical correspondence between the empirical expressions for the natural direct effect and the effect of exposure among the unexposed standardized by a binary confounder. They then exploit this correspondence to prove that the direction of the bias due to nondifferential measurement error in estimating the natural direct and indirect effects is to overestimate the natural direct effect and underestimate the natural indirect effect.
考虑一项研究,其中二元暴露对结果的影响部分通过二元中介起作用,但中介的测量存在非差异错误分类。假设研究人员希望估计暴露对结果的直接和间接影响。在本文中,作者描述了经验表达式之间的数学对应关系自然直接效应和暴露在未暴露的暴露之间的效应标准化通过二元混杂因素。然后,他们利用这种对应关系证明了由于自然直接和间接效应估计中的非差异测量误差而导致的偏差的方向是高估自然直接效应和低估自然间接效应。