classify_effect_modification
Classify effect-modification structures in causal DAGs into five types—direct, indirect, common-cause, proxy, pure-interaction—to clarify whether subgroup effects are interpretable as pure modification or require adjusted estimands.
Instructions
For each modifier annotation on the DAG, classify the effect-modification structure per VanderWeele & Robins (2007) and Weinberg (2007). The five types and their regulatory implications: • direct — modifier is structurally independent of the E-D system; subgroup-specific effects are interpretable as pure modification. • indirect — modifier acts through a mediator; subgroup effects conflate modification with mediation. • common-cause — modifier shares an ancestor with the exposure; subgroup effects are confounded unless the ancestor is also adjusted. • proxy — modifier is unobserved; subgroup analyses rest on a downstream proxy. • pure-interaction — modifier has a direct edge to the outcome; the appropriate estimand is the joint effect, not a subgroup-specific effect (Weinberg 2007).
Outputs are conditional on the encoded structure.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| dag | Yes | Canonical DAG with modifiers populated. |