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Two Approaches to Direct Estimation of Riesz Representers

David Bruns-Smith

arXiv 21 Mar 2026 · Econometrics

arXiv:2603.20936 · PDF · OpenAlex · Extracted main text

Abstract

The Riesz representer is a central object in semiparametric statistics and debiased/doubly-robust estimation. Two literatures in econometrics have highlighted the role for directly estimating Riesz representers: the automatic debiased machine learning literature (as in Chernozhukov et al., 2022b), and an independent literature on sieve methods for conditional moment models (as in Chen et al., 2014). These two literatures solve distinct optimization problems that in the population both have the Riesz representer as their solution. We show that with unregularized or ridge-regularized linear, sieve, or RKHS models, the two resulting estimators are numerically equivalent. However, for other regularization schemes such as the Lasso, or more general machine learning function classes including neural networks, the estimators are not necessarily equivalent. In the latter case, the Chen et al. (2014) formulation yields a novel constrained optimization problem for directly estimating Riesz representers with machine learning. Drawing on results from Birrell et al. (2022), we conjecture that this approach may offer statistical advantages at the cost of greater computational complexity.

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Most heavily cited references

The works this paper leans on most, across its whole bibliography — not restricted to papers in our corpus. Ranked by composite intensity, which combines how often a work is mentioned, how many sections mention it, and how much of that falls in the main text rather than the appendix.

ReferenceIntensityMentionsSectionsMain text
1Chen, Xiaohong and Liao, Zhipeng and Sun, Yixiao (2014) Sieve inference on possibly misspecified semi-nonparametric time series models1.000125100%
2Chernozhukov, Victor and Newey, Whitney K and Singh, Rahul (2022) Automatic debiased machine learning of causal and structural effects1.00085100%
3Chen, Xiaohong and Pouzo, Demian (2015) Sieve Wald and QLR inferences on semi/nonparametric conditional moment models0.92844100%
4Birrell, Jeremiah and Katsoulakis, Markos A and Pantazis, Yannis (2022) Optimizing variational representations of divergences and accelerating their statistical estimation0.92843100%
5Kanamori, Takafumi and Hido, Shohei and Sugiyama, Masashi (2008) Efficient direct density ratio estimation for non-stationarity adaptation and outlier detection0.73732100%
6Bruns-Smith, David and Dukes, Oliver and Feller, Avi and Ogburn, Eli… (2025) Augmented balancing weights as linear regression self0.64422100%
7Chen, Xiaohong and Hong, Han and Tamer, Elie (2005) Measurement error models with auxiliary data0.64422100%
8Lee, Kaitlyn J and Schuler, Alejandro (2025) RieszBoost: Gradient Boosting for Riesz Regression0.64422100%
9Sugiyama, Masashi and Takeuchi, Ichiro and Suzuki, Taiji and Kanamor… (2010) Conditional density estimation via least-squares density ratio estimation0.64422100%
10Ai, Chunrong and Chen, Xiaohong (2003) Efficient estimation of models with conditional moment restrictions containing unknown functions0.40511100%

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