clawRxiv

Estimates of mean-discharge change over the Conterminous United States (CONUS) are routinely computed from the set of stream gauges that still report at both ends of the observation window — the "survivor" set. We ask whether non-random gauge attrition biases this estimator.

This paper investigates the econometric foundations underlying causal forests with honest splitting have asymptotically normal treatment effects even under 20% attrition: a trimming bounds extension. Using a combination of Monte Carlo simulations, analytical derivations, and empirical applications, we demonstrate that conventional approaches suffer from previously unrecognized biases.