Generalized Second Price Auction with Probabilistic Broad Match

Generalized Second Price (GSP) auctions are widely used by search engines today to sell their ad slots. Most search engines have supported broad match between queries and bid keywords when executing GSP auctions, however, it has been revealed that GSP auction with the standard broad-match mechanism they are currently using (denoted as SBM-GSP) has several theoretical drawbacks (e.g., its theoretical properties are known only for the single-slot case and full-information setting, and even in this simple setting, the corresponding worst-case social welfare can be rather bad). To address this issue, we propose a novel broad-match mechanism, which we call the Probabilistic Broad-Match (PBM) mechanism. Different from SBM that puts together the ads bidding on all the keywords matched to a given query for the GSP auction, the GSP with PBM (denoted as PBM-GSP) randomly samples a keyword according to a predefined probability distribution and only runs the GSP auction for the ads bidding on this sampled keyword. We perform a comprehensive study on the theoretical properties of the PBM-GSP. Specifically, we study its social welfare in the worst equilibrium, in both full-information and Bayesian settings. The results show that PBM-GSP can generate larger welfare than SBM-GSP under mild conditions. Furthermore, we also study the revenue guarantee for PBM-GSP in Bayesian setting. To the best of our knowledge, this is the first work on broad-match mechanisms for GSP that goes beyond the single-slot case and the full-information setting

Entry and Exchanges of Cost Information

The literature on exchanges of information has ignored firms' entry decisions. Yet, the Federal Trade Commission recently expressed concerns that exchanges of information in business-to-business electronic platforms would adversely impact entry and, thus, consumers. When entry decisions are endogenized in a competitive Cournot model with cost uncertainty, we find results that contrast sharply with current thinking on the welfare consequences of information sharing.

On Bundling in Insurance Markets

This paper analyzes the welfare consequences of bundling different risks in one insurance contract in markets where adverse selection is important. This question is addressed in the context of a competitive insurance model a la Rothschild and Stiglitz (1976) with two sources of risk. Accordingly, there are four possible types of individuals and many incentive compatibility constraints to be considered. We show that the effect of bundling on these incentive compatibility constraints is such that bundling always yields a welfare improvement, and this result only holds when all four types have strictly positive shares in the population. Due to the competition between insurance companies, these benefits accrue to consumers who potentially have fewer contracts to choose from, but benefit from the better sorting possibilities due to bundling.

Should Urban Transit Subsidies Be Reduced?

This paper derives intuitive and empirically useful formulas for the optimal pricing of passenger transit and for the welfare effects of adjusting current fare subsidies, for peak and off-peak urban rail and bus systems. The formulas are implemented based on a detailed estimation of parameter values for the metropolitan areas of Washington (D.C.), Los Angeles, and London. Our analysis accounts for congestion, pollution, and accident externalities from automobiles and from transit vehicles; scale economies in transit supply; costs of accessing and waiting for transit service as well as service crowding costs; and agency adjustment of transit frequency, vehicle size, and route network to induced changes in demand for passenger miles. The results support the efficiency case for the large fare subsidies currently applying across mode, period, and city. In almost all cases, fare subsidies of 50% or more of operating costs are welfare improving at the margin, and this finding is robust to alternative assumptions and parameters.Transit subsidies; Scale economies; Traffic congestion; Welfare effects

Aggregate Representations of Aggregate Games

An aggregate game is a normal-form game with the property that each player’s payoff is a function only of his own strategy and an aggregate function of the strategy profile of all players. Aggregate games possess a set of purely algebraic properties that can often provide simple characterizations of equilibrium aggregates without first requiring that one solves for the equilibrium strategy profile. The defining nature of payoffs in an aggregate game allows one to project the n-player strategic analysis of a normal form game onto a lower-dimension aggregate-strategy space, thereby converting an n-player game to a simpler object – a self-generating single-person maximization program. We apply these techniques to a number of economic settings including competition in supply functions and multi-principal common agency games with nonlinear transfer functions.Aggregate games, common agency, asymmetric informa- tion, menu auctions

Efficiency and fairness in ambulance planning

Mei, R.D. van der [Promotor]Bhulai, S. [Promotor

Liquidity risks on power exchanges

Financial derivatives are important hedging tool for asset’s manager. Electricity is by its very nature the most volatile commodity, which creates big incentive to share the risk among the market participants through financial contracts. But, even if volume of derivatives contracts traded on Power Exchanges has been growing since the beginning of the restructuring of the sector, electricity markets continue to be considerably less liquid than other commodities. This paper tries to quantify the effect of this insufficient liquidity on power exchange, by introducing a pricing equilibrium model for power derivatives where agents can not hedge up to their desired level. Mathematically, the problem is a two stage stochastic Generalized Nash Equilibrium and its solution is not unique. Computing a large panel of solutions, we show how the risk premium and player’s profit are affected by the illiquidity.illiquidity, electricity, power exchange, artitrage, generalized Nash Equilibrium, equilibrium based model, coherent risk valuation

CREDIT-PRODUCT INTERLINKAGE, CAPTIVE MARKETS AND TRADE LIBERALIZATION IN AGRICULTURE: A THEORETICAL ANALYSIS IN AGRICULTURE: A THEORETICAL ANALYSIS

This paper builds a model of fragmented duopsony in backward agriculture following Basu and Bell (1991) in which the purchasers (traders) have captive markets each but compete in a contested market. We focus on the formation of captive markets through trader-farmer interlinkage in the form of interlinked credit-product contracts (ICPCs). ICPC (or the formation of captive markets) is not an entry-preventive strategy in the model. Its motive is to push the farmers to their reservation income level. However, the captive and the contested markets are linked by the requirement that the reservation income of a captive farmer has to equal the income of a farmer in the contested market. In general, in our model strategic considerations determine the extent of use of ICPCs rather than explaining their existence. In this set-up we examine the effects of trade liberalization in agriculture on the village economy. We show that a reduction in the credit subsidy will raise the size of the captive market, leads to deterioration in the welfare of the farmers and may lower the agricultural productivity of the economy. On the contrary, an increase in the international price of the crop unambiguously improves the welfare of the farmers but the effect on the agricultural productivity is ambiguous. The paper argues that unless the developed countries liberalize trade in their agricultural sector, it would be premature for the developing countries to go in for agricultural trade liberalization and remove all farm subsidies, as this policy may in fact be counterproductive.Trader, Farmer, Captive segment, Contested segment, Interlinkage, Nash equilibrium, Trade liberalization in agriculture