Philip Marx
Assistant Professor, LSU
Gulf Coast Coca-Cola Bottling Co. Professorship
Gulf Coast Coca-Cola Bottling Co. Professorship
Welcome to my website! I am an Assistant Professor at LSU, with interests in microeconomic and econometric theory. To me these interests are connected in two ways: first, the applications, which include developing new methods for quantifying discrimination, and second, the overarching toolkits, including causal inference and optimization. Previously I was a postdoc at Harvard University. Before that I completed my PhD at Northwestern University's Kellogg School of Management. Please don't hesitate to get in touch!
Published/Forthcoming Papers
"The ABC's of Who Benefits from Working with AI: Ability, Beliefs, and Calibration," with Andrew Caplin, David Deming, Shangwen Li, Daniel Martin, Ben Weidmann, and Kadachi Ye. Accepted, Management Science. Previously NBER Working Paper 33021. [Appendix].
"Modeling Machine Learning: A Cognitive Economic Approach," with Andrew Caplin and Daniel Martin. 2025. Journal of Economic Theory 224:105970.
"Rationalizable Learning," with Andrew Caplin and Daniel Martin. 2024. Economic Theory.
"Parallel Trends and Dynamic Choices," with Elie Tamer and Xun Tang. 2024. Journal of Political Economy Microeconomics 2(1), 129-171.
"Sharp Bounds in the Latent Index Selection Model." 2024. Journal of Econometrics 238(2), 105561.
"A Robust Test of Prejudice for Discrimination Experiments," with Daniel Martin. 2022. Management Science (Fast Track) 68(6), 4527-4536.
"An Absolute Test of Racial Prejudice." 2022. Journal of Law, Economics, and Organization 38(1), 42-91.
"Revenue from Matching Platforms," with James Schummer. 2021. Theoretical Economics 16(3), 799-824.
"Testing Capacity-Constrained Learning," with Andrew Caplin, Daniel Martin, Anastasiia Morozova, and Leshan Xu. arXiv:2502.00195.
Abstract: We introduce the first general test of capacity-constrained learning models. Cognitive economic models of this type share the common feature that constraints on perception are exogenously fixed, as in the widely used fixed-capacity versions of rational inattention (Sims 2003) and efficient coding (Woodford 2012). We show that choice data are consistent with capacity-constrained learning if and only if they satisfy a No Improving (Action or Attention) Switches (NIS) condition. Based on existing experiments in which the incentives for being correct are varied, we find strong evidence that participants fail NIS for a wide range of standard perceptual tasks: identifying the proportion of ball colors, recognizing shapes, and counting the number of balls. However, we find that this is not true for all existing perceptual tasks in the literature, which offers insights into settings where we do or do not expect incentives to impact the extent of attention.
"Heterogeneous Intertemporal Treatment Effects via Dynamic Panel Data Models," with Elie Tamer and Xun Tang. arXiv:2410.19060.
Abstract: We study the identification and estimation of heterogeneous, intertemporal treatment effects (TE) when potential outcomes depend on past treatments. First, applying a dynamic panel data model to observed outcomes, we show that instrument-based GMM estimators, such as Arellano and Bond (1991), converge to a non-convex (negatively weighted) aggregate of TE plus non-vanishing trends. We then provide restrictions on sequential exchangeability (SE) of treatment and TE heterogeneity that reduce the GMM estimand to a convex (positively weighted) aggregate of TE. Second, we introduce an adjusted inverse-propensity-weighted (IPW) estimator for a new notion of average treatment effect (ATE) over past observed treatments. Third, we show that when potential outcomes are generated by dynamic panel data models with homogeneous TE, such GMM estimators converge to causal parameters (even when SE is generically violated without conditioning on individual fixed effects). Finally, we motivate SE and compare it with parallel trends (PT) in various settings with observational data (when treatments are dynamic, rational choices under learning) or experimental data (when treatments are sequentially randomized).
Ph.D. , Managerial Economics and Strategy, Kellogg School of Management, Northwestern University, 2012-2017
B.S., Economics, B.S., Mathematics, summa cum laude, Tulane University, 2011