TY - JOUR
T1 - Clarifying causal mediation analysis for the applied researcher
T2 - Defining effects based on what we want to learn.
AU - Nguyen, Trang Quynh
AU - Schmid, Ian
AU - Stuart, Elizabeth A.
N1 - Publisher Copyright:
© 2020 American Psychological Association
PY - 2021
Y1 - 2021
N2 - The incorporation of causal inference in mediation analysis has led to theoretical and methodological advancements—effect definitions with causal interpretation, clarification of assumptions required for effect identification, and an expanding array of options for effect estimation. However, the literature on these results is fast-growing and complex, which may be confusing to researchers unfamiliar with causal inference or unfamiliar with mediation. The goal of this article is to help ease the understanding and adoption of causal mediation analysis. It starts by highlighting a key difference between the causal inference and traditional approaches to mediation analysis and making a case for the need for explicit causal thinking and the causal inference approach in mediation analysis. It then explains in as-plain-as-possible language existing effect types, paying special attention to motivating these effects with different types of research questions, and using concrete examples for illustration. This presentation differentiates 2 perspectives (or purposes of analysis): the explanatory perspective (aiming to explain the total effect) and the interventional perspective (asking questions about hypothetical interventions on the exposure and mediator, or hypothetically modified exposures). For the latter perspective, the article proposes tapping into a general class of interventional effects that contains as special cases most of the usual effect types—interventional direct and indirect effects, controlled direct effects and also a generalized interventional direct effect type, as well as the total effect and overall effect. This general class allows flexible effect definitions which better match many research questions than the standard interventional direct and indirect effects. (PsycInfo Database Record (c) 2021 APA, all rights reserved)
AB - The incorporation of causal inference in mediation analysis has led to theoretical and methodological advancements—effect definitions with causal interpretation, clarification of assumptions required for effect identification, and an expanding array of options for effect estimation. However, the literature on these results is fast-growing and complex, which may be confusing to researchers unfamiliar with causal inference or unfamiliar with mediation. The goal of this article is to help ease the understanding and adoption of causal mediation analysis. It starts by highlighting a key difference between the causal inference and traditional approaches to mediation analysis and making a case for the need for explicit causal thinking and the causal inference approach in mediation analysis. It then explains in as-plain-as-possible language existing effect types, paying special attention to motivating these effects with different types of research questions, and using concrete examples for illustration. This presentation differentiates 2 perspectives (or purposes of analysis): the explanatory perspective (aiming to explain the total effect) and the interventional perspective (asking questions about hypothetical interventions on the exposure and mediator, or hypothetically modified exposures). For the latter perspective, the article proposes tapping into a general class of interventional effects that contains as special cases most of the usual effect types—interventional direct and indirect effects, controlled direct effects and also a generalized interventional direct effect type, as well as the total effect and overall effect. This general class allows flexible effect definitions which better match many research questions than the standard interventional direct and indirect effects. (PsycInfo Database Record (c) 2021 APA, all rights reserved)
KW - causal mediation analysis
KW - effect definitions
KW - estimands
KW - interventional effects
KW - natural effects
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U2 - 10.1037/met0000299
DO - 10.1037/met0000299
M3 - Article
C2 - 32673039
AN - SCOPUS:85088472353
VL - 26
SP - 255
EP - 271
JO - Psychological Methods
JF - Psychological Methods
SN - 1082-989X
IS - 2
ER -