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Marginal structural models: much ado about (almost) nothing
Author(s) -
Shahar Eyal,
Shahar Doron J.
Publication year - 2013
Publication title -
journal of evaluation in clinical practice
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.737
H-Index - 73
eISSN - 1365-2753
pISSN - 1356-1294
DOI - 10.1111/j.1365-2753.2011.01757.x
Subject(s) - marginal structural model , confounding , weighting , nothing , axiom , set (abstract data type) , econometrics , mathematics , marginal distribution , statistics , computer science , medicine , philosophy , epistemology , random variable , geometry , radiology , programming language
Marginal structural models were developed to account for a so‐called time‐dependent confounder and to estimate the presumed effect of ‘treatment regime’ (treatment over time). We present a set of causal axioms, according to which the problem of time‐dependent confounding does not exist, and ‘treatment regime’ affects nothing. Per our axiomatization, marginal structural models do not introduce a new idea of deconfounding, but simply estimate a weighted average of effects. Whenever a weighted average and the weighting scheme can both be rationalized, the models are acceptable. Whenever a weighted average does not estimate an effect (e.g. important effect modification is ignored), or the weights are senseless – the models should not be fit.