Pham Thanh, Ha Trung, Soulakova Julia N
Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA.
Commun Stat Simul Comput. 2021;50(3):822-831. doi: 10.1080/03610918.2019.1568472. Epub 2019 Sep 9.
We discuss a two-step approach to test for a mediated effect using data gathered via complex sampling. The approach incorporates design-based multiple linear regressions and a generalized Sobel's method to test for significance of a mediated effect. We illustrate the applications to a study of nicotine dependence, race/ethnicity and cigarette purchase price among daily smokers in the U.S. The study goal was to assess significance of cigarette purchase price as a mediator in the association between race/ethnicity (non-Hispanic Black/African American, non-Hispanic White) and nicotine dependence measured in terms of the average number of cigarettes smoked per day. The single-mediator model incorporated 18 covariates as control factors. The results indicated a significant mediated effect of cigarette purchase price on the association. However, the relative effect size of 5% indicated low practical significance of the cigarette purchase price as a mediator in the association between race/ethnicity and nicotine dependence. The approach can be modified to studies where data are gathered via other types of complex sampling.
我们讨论了一种使用通过复杂抽样收集的数据来检验中介效应的两步法。该方法纳入了基于设计的多元线性回归和广义Sobel方法来检验中介效应的显著性。我们举例说明了该方法在美国每日吸烟者中对尼古丁依赖、种族/族裔和香烟购买价格的一项研究中的应用。该研究的目标是评估香烟购买价格作为种族/族裔（非西班牙裔黑人/非裔美国人、非西班牙裔白人）与以每日平均吸烟支数衡量的尼古丁依赖之间关联的中介变量的显著性。单中介模型纳入了18个协变量作为控制因素。结果表明香烟购买价格对该关联具有显著的中介效应。然而，5%的相对效应量表明香烟购买价格作为种族/族裔与尼古丁依赖之间关联的中介变量，其实际意义较低。该方法可修改后用于通过其他类型复杂抽样收集数据的研究。
