Vittinghoff E, Sen S, McCulloch C E
Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA, USA.
Stat Med. 2009 Feb 15;28(4):541-57. doi: 10.1002/sim.3491.
This paper presents sample size calculations for testing the mediation of the effect of a primary predictor by an intermediate variable. This problem is related to validating surrogate markers and to testing the effect of a primary predictor in the presence of confounders. For those problems, proposals for sample size calculation exist in the literature and can be adapted to the problem of mediation. Methods based on the variance inflation factor in linear regression provide exact sample size calculations for the linear model and approximations for the logistic, Poisson, and Cox models. We propose another procedure based on simulation of the underlying data structure, with applications to the logistic and Cox models. For the Poisson model, a new analytic method is also proposed. The behavior of the different proposals is investigated by means of simulation studies.
本文介绍了用于检验中间变量对主要预测变量效应的中介作用的样本量计算方法。这个问题与验证替代标志物以及在存在混杂因素的情况下检验主要预测变量的效应有关。对于这些问题，文献中存在样本量计算的建议，并且可以适用于中介作用问题。基于线性回归中方差膨胀因子的方法为线性模型提供了精确的样本量计算，为逻辑回归、泊松回归和Cox模型提供了近似计算。我们提出了另一种基于潜在数据结构模拟的方法，并将其应用于逻辑回归和Cox模型。对于泊松模型，还提出了一种新的解析方法。通过模拟研究来考察不同方法的性能。
