发表机构
University of Texas at El Paso; Independent Researcher（德克萨斯大学埃尔帕索分校; 独立研究者）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
针对不一致中介效应下PM指标失效的问题，提出MMS与抑制程度两个互补度量，量化间接通路绝对量级及其被抵消比例，并扩展至多条通路及二元结果场景。
AI 中文摘要
中介比例（PM）定义为间接效应除以总效应，当直接效应和间接效应方向相同时，该指标直观易懂。然而，在不一致中介效应下，相反的通路会部分相互抵消，导致PM超出单位区间，或当总效应趋近于零时变得不稳定。我们引入了两个互补的效应尺度度量：中介量级份额（MMS），它量化了间接通路相对于直接和间接通路绝对量级之和的绝对量级；以及抑制程度，它量化了被相反通路抵消的该组合量级的比例。我们确立了在两条通路情形下这两个度量的界限和极限行为，表明在一致中介效应下MMS退化为PM，并将这两个度量扩展到具有多条间接通路的场景。对于二元结果，我们通过使用对数将乘法效应转换为加法效应，将该框架扩展到比值比和风险比尺度，从而能够直接应用MMS和抑制程度。总之，这些度量提供了对通路方向不一致的中介系统的有界且可解释的表征。
英文摘要
The proportion mediated (PM), defined as the indirect effect divided by the total effect, is intuitive when direct and indirect effects operate in the same direction. Under inconsistent mediation, however, opposing pathways partially cancel each other, causing PM to fall outside the unit interval or become unstable as the total effect approaches zero. We introduce two complementary effect-scale measures: the Mediated Magnitude Share (MMS), which quantifies the absolute magnitude of an indirect pathway relative to the combined absolute magnitudes of the direct and indirect pathways, and the degree of suppression, which quantifies the fraction of this combined magnitude that is cancelled by opposing pathways. We establish the bounds and limiting behavior of both measures in the two-pathway case, show that MMS reduces to PM under consistent mediation, and extend both measures to settings with multiple indirect pathways. For binary outcomes, we extend the framework to odds-ratio and risk-ratio scales by using logarithms to convert multiplicative effects into additive ones, enabling direct application of MMS and the degree of suppression. Together, these measures provide bounded and interpretable characterizations of mediation systems in which pathway directions are not uniform.
Comments7 pages, 3 figures
