#proximal

2 notes

• Negative Control Outcome (NCO) An NCO is an outcome variable guaranteed a priori to be unaffected by the treatment's causal influence, yet still cast in the shadow of the same confounder $U$. By contrast, an NCE (negative control exposure) is an exposure with no causal effect on the outcome. If the "apparent effect" on an NCO is nonzero → a signal of unmeasured confounding (detection) → correct for it via proximal methods.
• Proximal Causal Inference When unmeasured confounding $U$ is present, the causal effect is identified using two types of proxies: