Estimating Aleatoric Uncertainty in the Causal Treatment Effect
Liyuan Xu, Bijan Mazaheri
TL;DR
The paper introduces the variance of the treatment effect $\mathrm{VTE}$ and the conditional variance $\mathrm{CVTE}(v)$ as principled measures of aleatoric uncertainty in causal treatment effects. It establishes identifiability from observational data under ignorability plus a discompositional assumption that $\mathbb{E}[Y^{(0)}Y^{(1)}|X]=\mathbb{E}[Y^{(0)}|X]\mathbb{E}[Y^{(1)}|X]$, and derives kernel-based nonparametric estimators with convergence guarantees for $f_a$ and $g_a$ used in the VTE/CVTE expressions. The estimators leverage kernel ridge regression and conditional mean embeddings to produce consistent estimates of $\mathrm{VTE}$ and $\mathrm{CVTE}$, respectively, and are validated on synthetic and semi-simulated data where they outperform naive baselines and demonstrate competitive performance. Overall, the work provides a rigorous, scalable framework for quantifying and decomposing intrinsic uncertainty in causal treatment effects, with potential implications for risk assessment in personalized interventions.
Abstract
Previous work on causal inference has primarily focused on averages and conditional averages of treatment effects, with significantly less attention on variability and uncertainty in individual treatment responses. In this paper, we introduce the variance of the treatment effect (VTE) and conditional variance of treatment effect (CVTE) as the natural measure of aleatoric uncertainty inherent in treatment responses, and we demonstrate that these quantities are identifiable from observed data under mild assumptions, even in the presence of unobserved confounders. We further propose nonparametric kernel-based estimators for VTE and CVTE, and our theoretical analysis establishes their convergence. We also test the performance of our method through extensive empirical experiments on both synthetic and semi-simulated datasets, where it demonstrates superior or comparable performance to naive baselines.
