check_overadjustment
Identify adjustment-set variables that bias causal estimates. Detects descendants of exposure, colliders, and descendants of colliders to flag overadjustment.
Instructions
Given a DAG and a proposed adjustment set, identify variables whose inclusion biases the estimate. Detects three failure modes: • descendant_of_exposure — variable is caused by the exposure; conditioning on it blocks part of the causal effect being estimated, changing the estimand (Schisterman 2009). • collider — variable is a collider on a non-causal X→Y path whose conditioning opens that path; conditioning is unjustified unless another set member re-blocks it. • descendant_of_collider — variable is downstream of an unconditioned collider; conditioning induces the same M-bias as conditioning on the collider directly (Greenland 2003).
Accepts either a canonical DAG object or a dagitty_string; both forms must be paired with adjustment_set.
Outputs are conditional on the encoded structure. DAG Studio verifies analyses given a DAG; it does not verify the DAG correctly encodes domain knowledge.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| dag | No | Canonical DAG object (nodes + edges + exposure + outcome). | |
| adjustment_set | Yes | Array of node ids proposed for adjustment. | |
| dagitty_string | No | Alternative DAG input: dagitty('dag { ... }') DSL. |