On the effects of joint bidding in independent private value auctions: An experimental study

This article explores the effect of a subset of symmetric bidders joining to bid together. Possible applications include mergers, collusion and joint-bidding arrangements. The change produces a “strong” party with a more advantageous value distribution than the remaining “weak” bidder(s). The predicted effects include inefficiency, a decrease in the sellerʼs revenue, and higher biddersʼ payoffs. Under risk neutrality, the members of the strong party benefit less than the weak bidders. The prediction is reversed when the bidders are sufficiently risk-averse. These hypotheses are tested experimentally. Contrary to the theory, joint bidding increases efficiency and the sellerʼs revenue decreases by less than expected. Strong bidders benefit more than weak bidders indicating that incentives to bid jointly may be greater than hypothesized. Additionally, the experiment assesses the effect of group decision-making. A Nash equilibrium prediction for individual–group differences based on differences in risk attitudes is not supported by the data.     

Multidimensional private value auctions

We consider parametric examples of symmetric two-bidder private value auctions in which each bidder observes her own private valuation as well as noisy signals about her opponent's private valuation. We show that, in such environments, the revenue equivalence between the first and second price auctions (SPAs) breaks down and there is no definite revenue ranking; while the SPA is always efficient allocatively, the first price auction (FPA) may be inefficient; equilibria may fail to exist for the FPA. We also show that auction mechanisms provide different incentives for bidders to acquire costly information about opponents’ valuation.     

An experimental study of auctions with a buy price under private and common values

eBayʼs Buy It Now format allows a seller to list an auction with a “buy price” at which a bidder may purchase the item immediately and end the auction. When bidders are risk averse, then theoretically a buy price can raise seller revenue when values are private (but not when values are common). We report the results of laboratory experiments designed to determine whether in practice a buy price is advantageous to the seller. We find that a suitably chosen buy price yields a substantial increase in seller revenue when values are private, and a small (but statistically insignificant) increase in revenue when values are common. In both cases a buy price reduces the variance of seller revenue. A behavioral model which incorporates the winnerʼs curse and the overweighting by bidders of their own signal explains the common value auction data better than the rational model.     

Optimistic irrationality and overbidding in private value auctions

Bidding one’s value in a second-price, private-value auction is a weakly dominant solution (Vickrey in J Finance 16(1):8–37, 1961), but repeated experimental studies find more overbidding than underbidding. We propose a model of optimistically irrational bidders who understand that there are possible gains and losses associated with higher bids but who may overestimate the additional probability of winning and/or underestimate the potential losses when bidding above value. These bidders may fail to discover the dominant strategy—despite the fact that the dominant strategy only requires rationality from bidders—but respond in a common sense way to out-of-equilibrium outcomes. By varying the monetary consequences of losing money in experimental auctions we observe more overbidding when the cost to losing money is low, and less overbidding when the cost is high. Our findings lend themselves to models in which less than fully rational bidders respond systematically to out-of-equilibrium incentives, and we find that our model better fits the effects of our manipulations than most of the existing models we consider.     

An experimental investigation of entry cost effects in sealed-bid dollar auctions

We experimentally study the effect of entry costs on bidding and entry behavior in common value auctions. We find, with entry costs, players bid lower in first price and higher in second price auctions, compared to no entry fee auctions.     

Asymmetric auctions with resale: An experimental study

We study auctions with resale based on Hafalir and Krishna's (2008) [6] model. As predicted, weak bidders bid more with resale than without, so that average auction prices tend to increase. When the equilibrium calls for weak types to bid higher than their values with resale they do, but not nearly as much as the theory predicts. In other treatments outcomes are much closer to the risk neutral Nash model's predictions. Bid distributions for weak and strong types are more similar with resale than without, in line with the theory.     

Premium auctions and risk preferences: An experimental study

In premium auctions, the highest losing bidder receives a reward from the seller. This paper studies the private value English premium auction (EPA) for different risk attitudes of bidders. We explicitly derive the symmetric equilibrium for bidders with CARA utilities and conduct an experimental study to test the theoretical predictions. In our experiment, subjects are sorted into risk-averse and risk-loving groups. We find that revenues in the EPA are significantly higher when bidders are risk loving rather than risk averse. These results are partly consistent with theory and confirm the general view that bidders' risk preferences constitute an important factor that affects bidding behavior and consequently also the seller's expected revenue. However, individual subjects rarely follow the equilibrium strategy and revenue in our experiment is lower than in the symmetric equilibrium.     

English auctions with resale: An experimental study

I design and test a simple English auction and two English auctions with resale, but with different informational backgrounds. All three treatments theoretically have the same equilibrium. I find, however, that the possibility of resale alters behavior significantly. In the two treatments with resale, subjects deviated from both the Nash prediction and the common results about bidding behavior in English auctions. Subjects tend to overbid, when they are certain they can reap the whole surplus in the resale market. I employ different models like QRE and levels of reasoning and conclude that overbidding can be explained as a rational response to the noisy environment in markets with human participants, that is, as rational decision making when anticipating others to make errors. When the outcome of the resale market is not certain, there is significant signaling behavior and auction prices tend to be lower than the Nash prediction.     

Bidding behavior in asymmetric auctions: An experimental study

We review an asymmetric auction experiment. Based on Plum (Int. J. Game Theory 20 (1992) 393) private valuations of the two bidders are independently drawn from distinct but commonly known distributions, one of which first-order stochastically dominates the other. We test the qualitative properties of that model of asymmetric auctions, in particular whether the weak bidder behaves more aggressively than the strong, and then test bidders’ preference for first- vs. second-price auctions.     

Abstract types and distributions in independent private value auctions

A large body of the mechanism design literature relies on convexity assumptions on the set of types (that is, on the domain of the mechanism). In this note I show that, at least for auction mechanisms with independent signals, it is always possible to extend incentive compatible mechanisms to incentive compatible mechanisms defined on any larger set of types. I acknowledge the comments of Luis Braido, Sérgio Orioli, Humberto Moreira, Frank Page and an anonymous referee. The financial support of Edital Universal 02/06, CNPq is gratefully acknowledged.     

Individual bidder behavior in first-price private value auctions

Individual bid functions display sensitivity to the strategic considerations inherent in first-price auctions. However, several formal models, including heterogeneous Nash equilibrium bidding models with constant relative risk aversion, perform quite poorly.     

An experimental investigation of the explosive effect in almost common value auctions

With only two bidders, a slight private value advantage in a common value auction is predicted to have an explosive effect on the allocation and revenue of the auction when using a second price and/or English clock mechanism. This paper uses the “wallet game” in an English clock mechanism with two players to test these predictions. The results show that the effect is proportional, not explosive, confirming the results of past experiments. A behavioral model with two types of players, naive and sophisticated, is developed and tested against the experimental data. In the model, naive players use a rule of thumb bidding function, while the sophisticated players are fully rational and, when forming their strategy (choosing the best response), correctly account for the probability that a rival is naive or sophisticated. We use cluster analysis to classify the players in the symmetric auctions as naive or sophisticated and a strict win/lose criteria to classify players in the asymmetric auctions. We find that those players classified as sophisticated are more aggressive in responding to high signals or advantaged status than their naive counterparts, but do not lower their bids relative to the naive players when receiving low signals or when regular.     

Entry decisions and bidding behavior in sequential first-price procurement auctions: An experimental study

Though many real life auctions are run independently of each other, from the bidders' point of view they often form sequences of auctions. We investigate how behavior responds to the additional incentives that are present in such auction sequences. Comparing subjects' decisions in single first-price procurement auctions with their decisions in a game consisting of two subsequent first-price procurement auctions, we find that, in line with the theoretical prediction, entry and bidding behavior is crucially affected by the opportunity cost of early bid submission. Though, entry decisions and average bids in the auction sequence systematically deviate from the perfect Bayesian equilibrium prediction. While the nature of the opponent (human being or computer) has no significant effect on these findings, giving subjects additional feedback on winners and prices seems to reduce the deviations from the equilibrium prediction.     

Discrete clock auctions: an experimental study

We analyze the implications of different pricing rules in discrete clock auctions. The two most common pricing rules are highest-rejected bid (HRB) and lowest-accepted bid (LAB). Under HRB, the winners pay the lowest price that clears the market; under LAB, the winners pay the highest price that clears the market. In theory, both the HRB and LAB auctions maximize revenues and are fully efficient in our setting. Our experimental results indicate that the LAB auction achieves higher revenues. This revenue result may explain the frequent use of LAB pricing. On the other hand, HRB is successful in eliciting true values of the bidders both theoretically and experimentally.     

Endogenous participation in charity auctions

Data from a recent field experiment suggests that differences in participation rates are responsible for much of the variations in charity auction revenues across formats. We provide a theoretical framework for the analysis of this and other related results. The model illustrates the limits of previous results that assume full participation and introduces some new considerations to the choice of auction mechanism. It also implies, however, that the data cannot be explained in terms of participation costs alone: there must exist mechanism-specific obstacles to participation.     

Creating competition out of thin air: An experimental study of right-to-choose auctions

This paper presents an experimental study of a mechanism that is commonly used to sell multiple heterogeneous goods. The novel feature of this procedure is that instead of selling each good in a separate auction, the seller executes a single auction in which buyers, who may be interested in completely different goods, compete for the right to choose a good. We provide experimental evidence that a Right-to-Choose (RTC) auction can generate more revenue than the theoretically optimal auction. Moreover, in contrast to the “optimal” auction, the RTC auction is approximately efficient in the sense that the surplus it generates is close to the maximal one. Furthermore, a seller who would like to retain some of his goods can generate more revenue with a restricted RTC auction in which not all rights-to-choose are sold, than with the theoretically optimal auction.     

Endogenous bid rotation in repeated auctions

I study collusion between two bidders in a general symmetric IPV repeated auction, without communication, side transfers, or public randomization. I construct a collusive scheme, endogenous bid rotation, that generates a payoff larger than the bid rotation payoff.     

Simultaneous versus sequential all-pay auctions: an experimental study

While both simultaneous and sequential contests are mechanisms used in practice such as crowdsourcing, job interviews and sports contests, few studies have directly compared their performance. By modeling contests as incomplete information all-pay auctions with linear costs, we analytically and experimentally show that the expected maximum effort is higher in simultaneous contests, in which contestants choose their effort levels independently and simultaneously, than in sequential contests, in which late entrants make their effort choices after observing all prior participants’ choices. Our experimental results also show that efficiency is higher in simultaneous contests than in sequential ones. Sequential contests’ efficiency drops significantly as the number of contestants increases. We also discover that when participants’ ability follows a power distribution, high ability players facing multiple opponents in simultaneous contests tend to under-exert effort, compared to theoretical predictions. We explain this observation using a simple model of overconfidence.     

Bundle and separate sales in auctions with entry

A seller sells dissimilar objects while taking the auction rule as given. Should the seller sell the objects separately or as a bundle? Generally, when the number of bidders is small bundling helps to stimulate the competition and raise revenue. In this paper, we show that if entry is costly enough the process of endogenous participation generates sufficient competition to make bundling unnecessary in auctions. Thus whether a bundle auction generates a higher or a lower revenue ultimately depends first on the level of the entry costs and then, possibly, on the number of potential bidders.