Zhenling Jiang

Yanhao 'Max' Wei, Zhenling Jiang

We explore pretraining estimators for structural econometric models. The estimator is "pretrained" in the sense that the bulk of the computational cost and researcher effort occur during the construction of the estimator. Subsequent applications of the estimator to different datasets require little computational cost or researcher effort. The estimation leverages a neural net to recognize the structural model's parameter from data patterns. As an initial trial, this paper builds a pretrained estimator for a sequential search model that is known to be difficult to estimate. We evaluate the pretrained estimator on 12 real datasets. The estimation takes seconds to run and shows high accuracy. We provide the estimator at pnnehome.github.io. More generally, pretrained, off-the-shelf estimators can make structural models more accessible to researchers and practitioners.

Ruohan Zhan, Shichao Han, Yuchen Hu et al.

Recommender systems are essential for content-sharing platforms by curating personalized content. To improve recommender systems, platforms frequently rely on creator-side randomized experiments to evaluate algorithm updates. We show that commonly adopted difference-in-means estimators can lead to severely biased estimates due to recommender interference, where treated and control creators compete for exposure. This bias can result in incorrect business decisions. To address this, we propose a ``recommender choice model'' that explicitly represents the interference pathway. The approach combines a structural choice framework with neural networks to account for rich viewer-content heterogeneity. Building on this foundation, we develop a debiased estimator using the double machine learning (DML) framework to adjust for errors from nuisance component estimation. We show that the estimator is $\sqrt{n}$-consistent and asymptotically normal, and we extend the DML theory to handle correlated data, which arise in our context due to overlapped items. We validate our method with a large-scale field experiment on Weixin short-video platform, using a costly double-sided randomization design to obtain an interference-free ground truth. Our results show that the proposed estimator successfully recovers this ground truth, whereas benchmark estimators exhibit substantial bias, and in some cases, yield reversed signs.