With reference to causal mediation analysis, a parametric expression for natural direct and indirect effects is derived for the setting of a binary outcome with a binary mediator, both modelled via a logistic regression. The proposed effect decomposition operates on the odds ratio scale and does not require the outcome to be rare. It generalizes the existing ones, allowing for interactions between both the exposure and the mediator and the confounding covariates. The derived parametric formulae are flexible, in that they readily adapt to the two different natural effect decompositions defined in the mediation literature. In parallel with results derived under the rare outcome assumption, they also outline the relationship between the causal effects and the correspondent pathway-specific logistic regression parameters, isolating the controlled direct effect in the natural direct effect expressions. Formulae for standard errors, obtained via the delta method, are also given. An empirical application to data coming from a microfinance experiment performed in Bosnia and Herzegovina is illustrated.

参考因果调解分析，得出自然直接和间接影响的参数表达式，用于通过二元调解器设置二元结果，两者均通过逻辑回归建模。拟议的效果分解在比值比例尺度上运行，并且不需要结果是稀有的。它概括了现有的变量，允许在曝光和中介之间以及混杂的协变量之间进行交互。派生的参数公式很灵活，因为它们很容易适应调解文献中定义的两种不同的自然效应分解。除了在罕见结果假设下得出的结果之外，他们还概述了因果效应与相应途径特定的逻辑回归参数之间的关系，在自然直接效应表达中分离受控直接效应。还给出了通过增量法获得的标准误差的公式。说明了在波斯尼亚和黑塞哥维那进行的小额信贷实验数据的经验应用。