The Methodology Center, The Pennsylvania State University, 204 E. Calder Way, Ste. 400, State College, PA 16801, USA.
Prev Sci. 2012 Aug;13(4):437-47. doi: 10.1007/s11121-011-0271-0.
Researchers often hypothesize that a causal variable, whether randomly assigned or not, has an effect on an outcome behavior and that this effect may vary across levels of initial risk of engaging in the outcome behavior. In this paper, we propose a method for quantifying initial risk status. We then illustrate the use of this risk-status variable as a moderator of the causal effect of leisure boredom, a non-randomized continuous variable, on cigarette smoking initiation. The data come from the HealthWise South Africa study. We define the causal effects using marginal structural models and estimate the causal effects using inverse propensity weights. Indeed, we found leisure boredom had a differential causal effect on smoking initiation across different risk statuses. The proposed method may be useful for prevention scientists evaluating causal effects that may vary across levels of initial risk.
研究人员经常假设一个因果变量（无论是否随机分配）对结果行为有影响，并且这种影响可能因初始参与结果行为的风险水平而异。在本文中，我们提出了一种量化初始风险状况的方法。然后，我们将该风险状况变量用作休闲无聊（一种非随机连续变量）对吸烟起始的因果效应的调节变量进行说明。数据来自南非健康智慧研究。我们使用边际结构模型定义因果效应，并使用逆倾向得分权重估计因果效应。实际上，我们发现休闲无聊对不同风险状况下的吸烟起始有不同的因果效应。所提出的方法可能对评估可能因初始风险水平而异的因果效应的预防科学家有用。
