Paul Sudhir R, Zaihra Tasneem
Department of Mathematics and Statistics, University of Windsor, 401 Sunset, Windsor, ON, Canada N9B 3P4.
Stat Med. 2008 Sep 20;27(21):4207-20. doi: 10.1002/sim.3289.
Risk difference (RD) is an important measure in epidemiological studies where the probability of developing a disease for individuals in an exposed group, for example, is compared with that in a control group. There are varying cluster sizes in each group and the binary responses within each cluster cannot be assumed independent. Under the cluster sampling scenario, Lui (Statistical Estimation of Epidemiological Risk. Wiley: CA, 2004; 7-27) discusses four methods for the construction of a confidence interval for the RD. In this paper we introduce two very simple methods. One method is based on an estimator of the variance of a ratio estimator (Sampling Techniques (3rd edn). Wiley: New York, 1977; 30-67) and the other method is based on a sandwich estimator of the variance of the regression estimator using the generalized estimating equations approach of Zeger and Liang (Biometrics 1986; 42:121-130). These two methods are then compared, by simulation, in terms of maintaining nominal coverage probability and average coverage length, with the four methods discussed by Lui (Statistical Estimation of Epidemiological Risk. Wiley: CA, 2004; 7-27). Simulations show at least as good properties of these two methods as those of the others. The method based on an estimate of the variance of a ratio estimator performs best overall. It involves a very simple variance expression and can be implemented with a very few computer codes. Therefore, it can be considered as an easily implementable alternative.
风险差异（RD）是流行病学研究中的一项重要指标，例如，在该研究中会比较暴露组个体患某种疾病的概率与对照组个体患该疾病的概率。每组中的聚类大小各不相同，且不能假定每个聚类内的二元反应是独立的。在整群抽样的情况下，Lui（《流行病学风险的统计估计》。Wiley：加利福尼亚州，2004年；第7 - 27页）讨论了构建风险差异置信区间的四种方法。在本文中，我们介绍两种非常简单的方法。一种方法基于比率估计量方差的估计器（《抽样技术》（第3版）。Wiley：纽约，1977年；第30 - 67页），另一种方法基于使用Zeger和Liang的广义估计方程方法（《生物统计学》，1986年；42：121 - 130）对回归估计量方差的三明治估计器。然后，通过模拟，将这两种方法在保持名义覆盖概率和平均覆盖长度方面与Lui（《流行病学风险的统计估计》。Wiley：加利福尼亚州，2004年；第7 - 27页）讨论的四种方法进行比较。模拟结果表明，这两种方法至少具有与其他方法一样好的性能。基于比率估计量方差估计的方法总体表现最佳。它涉及一个非常简单的方差表达式，并且可以用很少的计算机代码来实现。因此，它可以被视为一种易于实施的替代方法。
