Publications by Year: Working Paper

Working Paper
Chaney AJB, Stewart BM, Engelhardt BE. How Algorithmic Confounding in Recommendation Systems Increases Homogeneity and Decreases Utility. [Internet]. Working Paper. arXiv
Egami N, Fong CJ, Grimmer J, Roberts ME, Stewart BM. How to Make Causal Inferences Using Texts. Working Paper. ais.pdf
Horowitz M, Stewart B, Tingley D, Bishop M, Resnick L, Roberts M, Chang W, Mellers B, Tetlock P. What Makes Foreign Policy Teams Tick: Explaining Variation in Group Performance At Geopolitical Forecasting. Working Paper.

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Stewart BM. Latent Factor Regressions for the Social Sciences. Working Paper.Abstract

In this paper I present a general framework for regression in the presence of complex dependence structures between units such as in time-series cross-sectional data, relational/network data, and spatial data. These types of data are challenging for standard multilevel models because they involve multiple types of structure (e.g. temporal effects and cross-sectional effects) which are interactive. I show that interactive latent factor models provide a powerful modeling alternative that can address a wide range of data types. Although related models have previously been proposed in several different fields, inference is typically cumbersome and slow. I introduce a class of fast variational inference algorithms that allow for models to be fit quickly and accurately.

tensorreg.pdf tensorregappendix.pdf
Roberts ME, Stewart BM, Nielsen R. Matching Methods for High-Dimensional Data with Applications to Text. Working Paper.Abstract

Matching is a popular technique for preprocessing observational data to facilitate causal inference and reduce model dependence by ensuring that treated and control units are balanced along pre-treatment covariates. While most applications of matching balance on a small number of covariates, we identify situations where matching with thousands of covariates may be desirable, such as causal inference where confounders are measured with text. With high-dimensional covariates, traditional matching methods are less effective and may be difficult or impossible to implement. We characterize the problem of matching in a high-dimensional context as a tradeoff between dimension reduction and imbalance bounding. We develop a new method called Topical Inverse Regression Matching (TIRM) that optimizes this tradeoff by including both a low-dimensional projection of covariates and information about the probability of treatment. We illustrate our approach by estimating the effect of censorship on the writing of Chinese bloggers, the effects of gender on citation counts in international relations, and the effects of targeted killings and capture by counterterrorists on the popularity of jihadist writings.

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