My name is Olga Gorelkina and I am a lecturer in Economics at the University of Liverpool, UK. My research focuses on applications of game theory, in particular, mechanism design, auctions, and information economics. Prior to Liverpool I was part of Martin Hellwig's team at the Max Planck Institute for Research on Collective Goods in Bonn, and held a visiting position at the Cowles Foundation at Yale University. I earned my Ph.D at Toulouse School of Economics under the supervision of David Martimort. I hold a Master's degree from New Economic School and a Bachelor's degree from Moscow State University.
MECHANISM DESIGN & VOTING
Collusion via Information Sharing and Optimal Auctions [University of Liverpool Working Paper, 2018]
This paper studies collusion via information sharing in the context of auctions. The model of collusion via information sharing builds on Aumann’s (1976) description of knowledge. Robustness of auction mechanisms to collusion via information sharing is defined as the impossibility of an agreement to collude. A cartel can agree to collude on a contract if it is common knowledge within that cartel that the contract is incentive compatible and individually rational. Robust mechanisms are characterized in a number of settings where some, all, or no bidders are bound by limited liability. Finally, the characterization is used in a simple IPV setting to design a mechanism that is both optimal and robust to collusion.
Keywords: Bidder collusion, mechanism design, communication design, no-trade theorem.
The Expected Externality Mechanism in a Level-k Environment [International Journal of Game Theory, 2018]
Mechanism design theory relies on the concept of Nash equilibrium. However, studies of experimental games suggest that Nash equilibria are rarely played and provide evidence that subjects may be thinking only a finite number of iterations. Our purpose is to find out whether the expected externality mechanism (D'Aspremont, Gerard-Varet, 1979) retains its properties under finite-iterations thinking. While efficient implementation fails under certain conditions, our results provide a vindication of the mechanism in the convex quasi-linear environment with finitely rational agents.
Keywords: Expected Externality Mechanism, Level-k Model, Bounded Rationality.
This paper explores the effects of the straight-ticket voting option (STVO) on the positions of politicians. STVO, present in some U.S. states, allows voters to select one party for all partisan elections listed on the ballot, as opposed to filling out each office individually. We analyze the effects of STVO on policy-making by building a model of pre-election competition. STVO results in greater party loyalty of candidates, while increasing the weight of non-partisan voters' positions in candidate selection. This induces an asymmetric effect on winning probabilities and implemented policies in the two-party system.
Keywords: Ballot Design, Elections, Political Positions.
One Strike and You’re Out: The Effects of the Master Lever on Senator Positions [latest version] [earlier version: Max Planck Institute Preprint, 2016, online appendix], with Ioanna Grypari and Erin Hengel
We investigate the impact a straight-ticket voting option—a.k.a. the Master Lever—has on U.S. senators’ roll-call voting records in Congress. Using a difference-in-differences framework, we find the Master Lever leads to a 3–6 percent rightward shift in senators’ policy positions. The effect is largely driven by the Republican party. To interpret our results, we analyse the Master Lever’s impact on electoral incentives and outcomes. Our findings suggest that ballot design has a non-negligible impact on policy-making. They also imply that electoral outcomes in moderate to right-leaning Master Lever states may be especially vulnerable to right-wing, non-partisan voters.
Keywords: Ballot Design, Elections, Political Positions, U.S. Senate.
Estimate Based Dynamic Implementation [Max Planck Institute Preprint, 2014]
This paper introduces a virtually efficient mechanism in a setting with sequentially arriving agents who hold informative signals about future types. To reveal the information the principal organizes betting on future type reports. An agent’s betting reward depends on how accurately the prior updated on his report predicts the type reports observed in the following period. The mechanism satisfies participation constraints and generates no deficit after any reported history.
Keywords: Dynamic Mechanisms, Scoring Rule, Bayesian Learning, Conjugate Priors.
Bidder Collusion and the Auction with Target Bids [Max Planck Institute Preprint, 2014]
I study collusion in one-shot auctions, where a buyer can bribe his competitors into lowering their bids. I modify the single-unit Vickrey auction to incite deviations from the designated-winner scenario and thus undermine collusion. The construction of mechanism does not require the knowledge of the colluding bidders’ identities or distributions of valuations, in which sense it is entirely detail-free.
Keywords: Bidder Collusion, Detail-Free Auctions, Vickrey Auction.
Precluding Collusion in Auctions [Hausdorff Research Institute for Mathematics Preprint, 2010]
Collusive bidding in auctions jeopardizes the revenue to the seller. This paper describes a way to preclude strong and tacit subgroup collusion in a non-repeated auction environment, when cartels can commit to transfer exchange ex post, but not to reallocation. The robustness is attained by an optional assignment rule in a sealed-bid Vickrey auction, which is not applied in equilibrium, but serves as a credible threat to any collusive agreement aimed at generating an extra surplus. In the absence of benefits to collusion the backward-inducing bidders will not engage into collusive negotiations.
Keywords: Acceptable Correlated Equilibrium, Collusion, Detail-Free Auctions.
MARKETS & EXPERIMENTS
We study the division of trade surplus in a competitive market environment by conducting a natural field experiment on German eBay. Acting as a seller, we offer Amazon gift cards with face values of up to 500 Euro. Randomly arriving buyers, the subjects of our experiment, make price offers according to eBay rules. Using a novel decomposition method, we infer offered shares of trade surplus and find that the average share proposed to the seller amounts to 29%. Additionally, we document: (i) insignificant effects of stake size; (ii) poor use of strategically relevant public information; and (iii) behavioural differences between East and West German subjects.
Keywords: Field Experiment, Ultimatum Game, Surplus Division, Bargaining, Internet Trade, eBay.
Information Aggregation through Stock Prices and the Cost of Debt [Journal of Institutional and Theoretical Economics, 2018] [Max Planck institute Preprint, 2013], with Wolfgang Kuhle
This paper studies a firm’s optimal capital structure in an environment, where the firm’s stock price serves as a public signal for its credit worthiness. In equilibrium, equity investors choose how much information to acquire privately, which induces a positive relation between the amount of equity issued and the stock price signal’s precision. Thus, through its capital structure, the firm can internalize the informational externality that stock prices exert on bond yields. Firms with a strong fundamental therefore issue more equity and less debt than they would if the informational spill-over did not exist.
Keywords: Information Aggregation, Capital Structure, Sequential Markets, Market Depth.
Individuals often have to decide to which degree of risk they want to expose others, or how much risk to accept if their choice has an externality on third parties. One typical application is a household. We exploit the opportunity to run an experiment in the German Socio-Economic Panel with two members from 494 households. Participants have a good estimate of each other’s risk preferences, even if not explicitly informed. They do not simply match this preference when deciding on behalf of the other household member, but shy away from exposing others to risk. We model the situation, and we find four distinct types of individuals, and two distinct types of households.
Keywords: SOEP-IS, Risk Attitudes, Aggregation of Preferences, Household Decision Making.