no code implementations • 25 Jul 2023 • Andrew Bennett, Nathan Kallus, Xiaojie Mao, Whitney Newey, Vasilis Syrgkanis, Masatoshi Uehara
We consider estimation of parameters defined as linear functionals of solutions to linear inverse problems.
no code implementations • 13 Jun 2023 • Jian Chen, Zhehao Li, Xiaojie Mao
The labeled data distribution may substantially differ from the full population, especially when the historical decisions and the target outcome can be simultaneously affected by some unobserved factors.
no code implementations • 4 Apr 2023 • Yong Liang, Xiaojie Mao, Shiyuan Wang
We study an online joint assortment-inventory optimization problem, in which we assume that the choice behavior of each customer follows the Multinomial Logit (MNL) choice model, and the attraction parameters are unknown a priori.
no code implementations • 10 Feb 2023 • Andrew Bennett, Nathan Kallus, Xiaojie Mao, Whitney Newey, Vasilis Syrgkanis, Masatoshi Uehara
In this paper, we study nonparametric estimation of instrumental variable (IV) regressions.
no code implementations • 17 Aug 2022 • Andrew Bennett, Nathan Kallus, Xiaojie Mao, Whitney Newey, Vasilis Syrgkanis, Masatoshi Uehara
In a variety of applications, including nonparametric instrumental variable (NPIV) analysis, proximal causal inference under unmeasured confounding, and missing-not-at-random data with shadow variables, we are interested in inference on a continuous linear functional (e. g., average causal effects) of nuisance function (e. g., NPIV regression) defined by conditional moment restrictions.
1 code implementation • 19 Feb 2022 • Nathan Kallus, Xiaojie Mao, Kaiwen Wang, Zhengyuan Zhou
Thanks to a localization technique, LDR$^2$OPE only requires fitting a small number of regressions, just like DR methods for standard OPE.
no code implementations • 15 Feb 2022 • Guido Imbens, Nathan Kallus, Xiaojie Mao, Yuhao Wang
In this paper, we uniquely tackle the challenge of persistent unmeasured confounders, i. e., some unmeasured confounders that can simultaneously affect the treatment, short-term outcomes and the long-term outcome, noting that they invalidate identification strategies in previous literature.
no code implementations • 25 Mar 2021 • Nathan Kallus, Xiaojie Mao, Masatoshi Uehara
Previous work has relied on completeness conditions on these functions to identify the causal parameters and required uniqueness assumptions in estimation, and they also focused on parametric estimation of bridge functions.
no code implementations • 5 Nov 2020 • Yichun Hu, Nathan Kallus, Xiaojie Mao
While one may use off-the-shelf machine learning methods to separately learn a predictive model and plug it in, a variety of recent methods instead integrate estimation and optimization by fitting the model to directly optimize downstream decision performance.
1 code implementation • 17 Aug 2020 • Nathan Kallus, Xiaojie Mao
We study contextual stochastic optimization problems, where we leverage rich auxiliary observations (e. g., product characteristics) to improve decision making with uncertain variables (e. g., demand).
no code implementations • 27 Mar 2020 • Nathan Kallus, Xiaojie Mao
However, there is often an abundance of observations on surrogate outcomes not of primary interest, such as short-term health effects or online-ad click-through.
1 code implementation • 30 Dec 2019 • Nathan Kallus, Xiaojie Mao, Masatoshi Uehara
A central example is the efficient estimating equation for the (local) quantile treatment effect ((L)QTE) in causal inference, which involves as a nuisance the covariate-conditional cumulative distribution function evaluated at the quantile to be estimated.
1 code implementation • 5 Sep 2019 • Yichun Hu, Nathan Kallus, Xiaojie Mao
We study a nonparametric contextual bandit problem where the expected reward functions belong to a H\"older class with smoothness parameter $\beta$.
1 code implementation • 1 Jun 2019 • Nathan Kallus, Xiaojie Mao, Angela Zhou
In this paper we study a fundamental challenge to assessing disparate impacts in practice: protected class membership is often not observed in the data.
1 code implementation • 27 Nov 2018 • Jiahao Chen, Nathan Kallus, Xiaojie Mao, Geoffry Svacha, Madeleine Udell
We also propose an alternative weighted estimator that uses soft classification, and show that its bias arises simply from the conditional covariance of the outcome with the true class membership.
no code implementations • 5 Oct 2018 • Nathan Kallus, Xiaojie Mao, Angela Zhou
We study the problem of learning conditional average treatment effects (CATE) from observational data with unobserved confounders.
1 code implementation • NeurIPS 2018 • Nathan Kallus, Xiaojie Mao, Madeleine Udell
Valid causal inference in observational studies often requires controlling for confounders.