PhD Candidate
Columbia University
Department of Economics
I will be available for interviews at the 2019 ASSA meetings
Click for contact info.
Columbia University, Department of Economics
420 West 118 Street
New York, NY, 10025
Email:
[email protected]
Click to flip back
References:
Yeon-Koo Che
[email protected]
Navin Kartik
[email protected]
Qingmin Liu
[email protected]
Click to flip back
I study a dynamic model in which a decision maker (DM) acquires information about the payoffs of different alternatives prior to making her decision. The key feature of the model is the flexibility of information: the DM can choose any dynamic signal process as an information source, subject to a flow cost that depends on the informativeness of signal. Under the optimal policy, the DM looks for a signal that arrives according to a Poisson process. The optimal Poisson signal confirms the DM's prior belief and is so accurate as to warrant an immediate action from the DM. Over time, absent arrival of a Poisson signal, the DM continues seeking a Poisson signal that is increasingly more precise but arrives less frequently.
"An auctioneer with limited commitment and many bidders achieves at most the profit from an efficient auction."
We study the role of limited commitment in a standard auction environment. In each period, the seller can commit to an auction with a reserve price but not future auctions.We characterize the set of equilibrium profits attainable for the seller as the period length vanishes. An immediate sale by efficient auction is optimal when there are at least three buyers. For many natural distributions two buyers is enough. Otherwise, we give conditions under which the maximal profit is attained through continuously declining reserve prices.
"Under indirect information measure from sequential cost minimization, Poisson learning is the optimal dynamic learning strategy"
I study the robust predictions of optimal learning dynamics in information acquisition problems where the measure of signal informativeness is an indirect measure from sequential cost minimization. I first show that an indirect information measure is supported by sequential cost minimization iff it satisfies: 1) monotonicity in Blackwell order, 2) sub-additivity in compound experiments and 3) linearity in mixing with no information. In a dynamic learning problem, if the cost of information depend on an indirect information measure and delay cost is fixed, then the optimal solution involves direct Poisson signals: arrival of signals directly suggest the optimal actions, and non-arrival of signal provides no information.
"Poisson learning creates most dispersed decision time distribution"
I consider the sequential implementation of a target information structure. I characterize the set of decision time distributions induced by all signal processes that satisfies a per-period learning capacity constraint. The maximal and minimal elements of the set by mean-preserving spread order are deterministic distribution and exponential distribution. The result implies that when time preference is risk loving (e.g. standard or hyperbolic discounting), Poisson signal is optimal since it induces the most risky exponential decision time distribution. When time preference is risk neutral (e.g. constant delay cost), all signal processes are equally optimal.
"Monopolistic seller of information should design a rich menu to screen buyers holding private information."
I consider the monopolistic pricing of informational good. A buyer's willingness to pay for information is from inferring the unknown payoffs of actions in decision making. A monopolistic seller and the buyer each observes a private signal about the payoffs. The seller's signal is binary and she can commit to sell any statistical experiment of her signal to the buyer. Assuming that buyer's decision problem involves rich actions, I characterize the profit maximizing menu. It contains a continuum of experiments, each containing different amount of information. I also find a complementarity between buyer's private information and information provision: when buyer's private signal is more informative, the optimal menu contains more informative experiments.
"A characterization of payoffs implementable through information design in a bargaining game."
Consider a canonical bargaining problem: a buyer makes a take-it-or-leave-it offer to a seller for a single object. The two parties’ values may be interdependent. We study the set of payoff vectors that can be implemented (in sequential equilibria) using joint information design. We establish, in part constructively, that the set is a triangle characterized by simple feasibility and individual-rationality constraints. We also investigate what is implementable only using information structures in which the seller is more informed than the buyer, or more generally, under a “no signaling” equilibrium restriction. We show that there is then no loss in providing the buyer with no information and only varying the seller’s information; i.e., familiar adverse-selection structures emerge. Our model encompasses monopoly pricing, for which our results augment those of Bergemann, Brooks, and Morris (2015) and Roesler and Szentes (2017).
"In a decentralized market, rating-guided search involves informational externality and endogenously creates statistical discrimination."
We consider a decentralized market where buyers search to trade with sellers of unknown quality. Each buyer targets sellers based on their ratings — a coarse summary (e.g. average) of the seller’s quality collected from previous transactions involving these sellers. We study the implication of a novel informational externality in the rating-guided market: the informational content of the sellers’ ratings is endogenous, depending on the frequency of their trading, but buyers make trading decisions not taking into account their informational effects. First, we show that an improvement in the ratings technology may exacerbate the informational externality, and hence can be welfare-worsening. Second, we extend the baseline model to allow for two ex ante identical demographic groups, and show that the informational externality endogenously generates statistical discrimination. In a stable equilibrium, highly-rated sellers (or workers) in the advantaged group receive more attention than highly-rated sellers (or workers) in the disadvantaged group, leading to discrimination against the latter group in a self-fulfilling fashion. Our analysis implies that an affirmative action policy restores equality, but only in the short run, as the non-discriminative equilibrium is unstable.
Some useful technical results & interesting preliminary analyses.
Download my Curriculum Vitae here.
References
Professor Yeon-Koo Che
Columbia University
(212) 854-8276
[email protected]
Professor Navin Kartik
Columbia University
(212) 854-3296
[email protected]
Professor Qingmin Liu
Columbia University
(212) 854-2512
[email protected]
Download my Curriculum Vitae here.
Download my Curriculum Vitae here.