Background and interests
Theo Offerman is professor of Behavioral Game Theory at the Department of Economics of the University of Amsterdam. His research interests include experimental economics, game theory and behavioral economics. Theo is a research fellow of the Royal Netherlands Academy of Arts and Sciences (KNAW) and a research fellow of Tinbergen Institute.
(2008) Noisy Signaling: Theory and Experiment PDF-file instructions
We investigate a noisy signaling game, in which nature adds random noise to the message chosen. Theoretically, with an unfavorable prior the separating equilibrium vanishes for low noise. It reappears for intermediate and high noise, where messages increase with noise. A pooling equilibrium always exists. In our experiment, noise works as an empirical equilibrium selection device. When noise increases, the separating equilibrium loses ground to the pooling equilibrium. Subjects separate for low noise where no separating equilibrium exists. Conditional on aiming for separation, high-quality senders choose messages that increase monotonically with noise. A simple behavioral explanation organizes the data well.
(2007) Guilt Driven Reciprocity in a Psychological Signaling Game PDF-file
We propose a theory of reciprocity according to which reciprocal behavior is driven by a donor's guilt. Through an experiment we show that subjects respond to factors which induce guilt but do not reflect allocative equity or intention. When the guilt inducing factor is privately observed by the donor, a psychological signaling game results. We solve for the separating and pooling equilibria. In a separating equilibrium, the donor distorts her gift to signal a low level of the guilt inducing factor, leading to a lower average gift than under full information. Our experiment confirms this implication of the separating equilibrium.
(2006) Demand Reduction and Preemptive Bidding in License Auctions PDF-file
Multi-unit ascending auctions allow for equilibria in which bidders strategically reduce their demand and split the market at low prices. At the same time, they allow for preemptive bidding by incumbent bidders in a coordinated attempt to exclude entrants from the market. We consider an environment where both demand reduction and preemptive bidding are supported as equilibrium phenomena of the ascending auction. In a series of experiments, we compare its performance to that of the discriminatory auction. Strategic demand reduction is quite prevalent in the ascending auction even when entry imposes a (large) negative externality on incumbents. As a result, the ascending auction performs worse than the discriminatory auction both in terms of revenue and efficiency, while entrants' chances are similar across the two formats.
(forthcoming) Fighting Collusion in Auctions: An Experimental Investigation International Journal of Industrial Organization PDF-file
The danger of collusion presents a serious challenge for auctioneers. In this paper, we compare the collusive properties of two standard auctions, the English auction and the first-price sealed-bid auction, and a lesser-known format, the Amsterdam (second-price) auction. In the Amsterdam auction, the highest losing bidder earns a premium for stirring up the price. We study two settings: in one, all bidders can collude, and in another, only a subset is eligible. The experiments show that the Amsterdam auction triggers less collusion than the standard auctions. We compare experimental results to theoretical predictions, and provide an explanation where they differ.
(forthcoming) Imitation and Luck: An Experimental Study on Social Sampling Games and Economic Behavior PDF-file
In this paper, we present the results of two experiments on social sampling. In both experiments, people are asked to make a risky decision in a situation where an idiosyncratic luck term affects their performance. Before they make their decision, people have the opportunity to sample others who have done exactly the same problem before them. These previous participants are ranked on the basis of their success. In the first experiment, we find that, by and large, subjects sample and imitate lucky risk seekers, while they could have sampled others to retrieve information that is valuable to solve their problem rationally. The simple behavioral rule of imitating the best appears to be robust to the setting of the problem. In the second experiment, we find that subjects tend to imitate successful others in both the winner's curse version and the loser's curse version of the Bazerman-Samuelson takeover game. Because of the way these problems are constructed, imitation exacerbates the winner's curse while it alleviates the loser's curse. In all problems, social sampling makes people look more risk seeking than the people who do not have the opportunity to sample.
(2009) A Truth-Serum for Non-Bayesians: Correcting Proper Scoring Rules for Risk Attitudes Review of Economic Studies 76, 1461-1489 Link to article Background material
Proper scoring rules provide convenient and highly efficient tools for incentive compatible elicitations of subjective beliefs. As traditionally used, however, they are valid only under expected value maximization. This paper shows how they can be generalized to modern (“nonexpected utility”) theories of risk and ambiguity, yielding mutual benefits: people using proper scoring rules can benefit from the empirical realism of nonexpected utility, and people analyzing ambiguity attitudes can benefit from the efficient measurements through proper scoring rules. An experiment demonstrates the feasibility of our generalized proper scoring rule.
(2008) Creating Competition Out of Thin Air: An Experimental Study of Right-to-Choose Auctions Games and Economic Behavior 62, 383-416 PDF-file
This paper presents an experimental study of a mechanism that is commonly used to sell multiple heterogenous 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.
(2008) Explaining the comparative statistics in step-level public good games C.R. Plott and V.L. Smith (eds) The Handbook of Experimental Economics Results volume 1 Amsterdam: North-Holland 817-824
(2006) Using First-Price Auctions to Sell Heterogeneous Licenses International Journal of Industrial Organization 24, 555-581 PDF-file
This paper considers three alternative ways to sell heterogenous licenses via a first-price format when there is single unit demand. It has been suggested that incorporating a first-price element may bolster competition in this case (Klemperer, 2002). In a controlled laboratory setting, we compare the performance of the simultaneous first-price auction, the sequential first-price auction and the simultaneous descending auction with that of the simultaneous ascending auction. The experiments involve several bidding environments of varying complexity. We find that the simultaneous ascending auction achieves the highest levels of efficiency but also has drawbacks: (i) its revenues are low and variable, (ii) per-license profits vary, and (iii) the incidence of winner's curse outcomes is high. Seller's revenues are highest when the licenses are sold in a sequential first-price auction, in decreasing order of quality.
(2006) Does Auctioning of Entry Licenses Induce Collusion? An Experimental Study Review of Economic Studies 73, 769-791 PDF-file
We use experiments to examine whether the auctioning of entry rights affects the behavior of market entrants. Standard economic arguments suggest that the license fee paid at the auction will not affect pricing since it constitutes a sunk cost. This argument is not uncontested though and this paper puts it to an experimental test. Our results indicate that an auction of entry licenses may affect prices in oligopoly but not in monopoly. In oligopoly, the payment of an entry fee increases the probability that the market entrants tacitly coordinate on a collusive price path.
(2004) The Amsterdam Auction. Econometrica 72, 281-94
The Amsterdam auction has been used to sell real estate in the Dutch capital for centuries. By awarding a premium to the highest losing bidder, the Amsterdam auction favors weak bidders without having the implementation difficulties of Myerson s (1981) optimal auction. In a series of experiments, we compare the standard first-price and English auctions, the optimal auction, and two variants of the Amsterdam auction. With strongly asymmetric bidders, the second-price Amsterdam auction raises substantially more revenues than standard formats and only slightly less than the optimal auction.
(2004) What's Causing Overreaction? An Experimental Investigation of Recency and the Hot Hand Effect Scandinavian Journal of Economics 106, 533-553 Link to article
A substantial body of empirical literature provides evidence for overreaction in markets. Past losers outperform past winners in stock markets as well as in sports markets. Two hypotheses are consistent with this observation. The recency hypothesis states that traders overweight recent information. Thus, they are too optimistic about winners and too pessimistic about losers. According to the hot hand hypothesis, traders try to discover trends in the past record of a firm or a team, and thereby overestimate the autocorrelation in the series. An experimental design allows us to distinguish between these hypotheses. The evidence is consistent with the hot hand hypothesis. Experience slightly reduces the observed phenomenon of overreaction.
(2003) Competitive Bidding in Auctions with Private and Common Values. Economic Journal 113, 598-613 Link to article
The objects for sale in most auctions possess both private and common value elements. This salient feature has not yet been incorporated into a strategic analysis of equilibrium bidding behaviour. This paper reports such an analysis for a stylised model in which bidders receive a private value signal and an independent common value signal. We show that more uncertainty about the common value has a negative effect on efficiency. Information provided by the seller decreases uncertainty, which raises efficiency and seller s revenues. Efficiency and revenues are also higher when more bidders enter the auction.
(2003) Winner s Curse without Overbidding. European Economic Review 47, 625-44 Link to article
We report the results of a series of second-price auction experiments where each bidder s signal is given by a normally distributed value plus a normally distributed error. While bidders values differ in one treatment they are the same in another, which allows for a direct test of the winner s curse irrespective of confounding factors. Bidders may also fall prey to a news curse when they do not sufficiently take into account that signals and errors are correlated. We find that the effects of the winner s curse are mitigated by a news curse and loss or risk aversion.
(2002) Competition For vs On the Rails: A Laboratory Experiment International Economic Review 43, 709-736
Several European countries and Japan are in various stages of privatizing and/or introducing more competition in passenger rail service. This process has been furthered by a directive from the Commission of the European Communities (1991) requiring member states to separate operations from infrastructure on the books and give international groupings of trains access to their infrastructure. In the Netherlands, the Ministry of Transport, Public Works, and Water Management was assigned responsibility for making a recommendation to Parliament for choosing between competition for the rails and competition on the rails in increasing competition in the supply of passenger rail service. The Ministry commissioned the experiments reported here in order to acquire better understanding of the properties of the two alternative types of competition in the context of a simple stylized rail network. The experimental rail network includes station complementarity and time slot substitutability. It also includes tradeoffs between local and express trains. Competition on the rails involves allocation of rights to use station and time slot routes by price bids in a combinatorial auction. Competition for the rails involves allocation of rights to regional monopolies by fare-structure bids for supplying a pre-specified minimum transport schedule. The experiments include both allocation of rights and scheduling of trains on the network. The two forms of competition are evaluated with various criteria developed by the Ministry, including market prices and allocative efficiency.
(2002) Are family transfers crowded out by public transfers? Scandinavian Journal of Economics 104, 587-604
(2002) Efficiency in Auctions with Private and Common Values: An Experimental Study. American Economic Review 92, 625-43
Auctions are generally not efficient when the object s expected value depends on private and common value information. We report a series of first-price auction experiments to measure the degree of inefficiency that occurs with financially motivated bidders. While some subjects fall prey to the winner s curse, they weigh their private and common value information in roughly the same manner as rational bidders, with observed efficiencies close to predicted levels. Increased competition and reduced uncertainty about the common value positively affect revenues and efficiency. The public release of information about the common value also raises efficiency, although less than predicted.
(2002) Hurting Hurts More Than Helping Helps. European Economic Review 46, 1423-37 Link to article
Previous experimental work suggests that both a dislike for an unequal division of payoffs and intentionality play a role to explain reciprocal behavior. This paper focuses on intentionality, and in particular on the question of whether negative intentionality matters more than positive intentionality. Experimental evidence obtained in the
(2002) Imitation and Belief Learning in an Oligopoly Experiment. Review of Economic Studies 69, 973-97
We examine the force of three types of behavioural dynamics in quantity-setting triopoly experiments: (1) mimicking the successful firm, (2) rules based on following the exemplary firm, and (3) rules based on belief learning. Theoretically, these three types of rules lead to the competitive, the collusive, and the Cournot-Nash outcome, respectively. In the experiment we employ three information treatments, each of which is hypothesized to be conducive to the force of one of the three dynamic rules. To a large extent, the results are consistent with the hypothesized relationships between treatments, behavioural rules, and outcomes.
(2001) Cooperation in an Overlapping Generations Experiment. Games and Economic Behavior 36, 264-75 Link to article
Recent theoretical work shows that folk theorems can be developed for infinite overlapping generations games. Cooperation in such games can be sustained as a Nash equilibrium. But, of course, there are other equilibria. This paper investigates experimentally whether cooperation actually occurs in a simple overlapping generations game. Subjects both play the game and formulate strategies. Our main finding is that subjects fail to exploit the intertemporal structure of the game. Even when we provided subjects with a recommendation to play the grim trigger strategy, most of the subjects still employed safe history-independent strategies.
(2001) Expectation Formation in Step-Level Public Good Games. Economic Inquiry 39, 250-69 Link to article
This article focuses on the process of expectation formation. Specifically, the question is addressed whether individuals think strategically when they form beliefs about other players behavior. Most belief learning models assume that people abstract from strategic considerations. Using an incentive-compatible mechanism, experimental data are obtained on subjects expectations in a step-level public good game and in a game against nature. Beliefs in the interactive games develop in the same way as in the game against nature, providing evidence that strategic considerations do not play a role. The evidence is consistent with predictions derived from the naive Bayesian model.
(1999) Strategic Behavior in Public Good Games: When Partners Drift Apart. Economics Letters 62, 35-41 Link to article Expanded working paper
(Abstract of the expanded Working Paper) We use a new design to (re)examine the occurrence of strategic behavior in voluntary contributions mechanism experiments. Subjects are in groups that remain constant for a number of periods before they change. The change is public knowledge and always consists of one member switching to another group. Moreover, everyone knows that this individual will not be grouped with any of the members again. In this sense 'partners' really become 'strangers'. We find considerable evidence of strategic behavior in these relatively simple games. Subjects who leave their group contribute less than in the previous period and less than in the next period in their new group. Contribution levels decline with the number of periods remaining for the group. The results can be explained by the occurrence of conditional cooperators, who are willing to contribute if and only if enough others do the same. The presence of these subjects elicits strategic (forward looking) behavior from others.
(1998) Learning by Experience and Learning by Imitating Successful Others. Journal of Economic Behavior and Organization 34, 559-75 Link to article
It is examined whether individuals learn from experience and/or by imitation. Usually individual judgmental learning displays systematic biases against the ideal Bayesian model. Imitation of successful others may decrease such effects. In an experiment, subjects make investment decisions and report expectations. The profitability of an investment depends on the realization of a stationary distribution of states of the world. In the baseline, subjects do not receive information about others expectations; in the other conditions, subjects perceive the expectations of others who observed either exactly the same events or different events from the same distribution. The results indicate that people learn both from experience and by imitating successful others.
(1998) Quantal Response Models in Step-Level Public Good Games. European Journal of Political Economy 14, 89-100 Link to article
The effect of adding noise to both an equilibrium model and a naive Bayesian model of behavior in step-level public good games is studied. Quantal response equilibria are derived for these games and a naive Bayesian quantal response function is presented. The models are fit for experimental data from such a game and compared. The results seem more promising for the naive Bayesian model than for the equilibrium model.
(1998) Public Good Provision and Public Bad Prevention: The Effect of Framing. Journal of Economic Behavior and Organization 34, 143-61 Link to article
An experimental analysis of voluntary, binary contributions for step-level public goods/bads is presented. Alternatively, the situation is presented as the provision of a public good or the prevention of a public bad. From a strategic point of view, these presentations are equivalent. In early periods of the twenty round experiments, behavior is indeed observed to be similar in both cases but, after about five periods, differences start to occur that grow larger. A simple learning model is developed that replicates the patterns in the experiments. Extrapolation beyond twenty periods show that the pattern observed reflects an equilibrium selection.
(1997) Beliefs and Decision Rules in Public Good Games (eds) Theory and Experiments Kluwer, Dordrecht/Boston/London
(1996) Value Orientations, Expectations and Voluntary Contributions in Public Goods. Economic Journal 106, 817-45 Link to article
An experimental analysis of voluntary, binary contributions for step-level public goods is presented. Independent information is obtained on individual value orientation and expectations about the behavior of other subjects using incentive compatible mechanisms. The effects of increasing payoffs for the public good and of decreasing groupsize are investigated. Attention is focused on the determination of expectations, the use of expectations when deciding on behavior, and differences in expectations and behavior between individuals with different value orientations.
e-mail: T.J.S.Offerman@uva.nl
phone: +31 (0)20 525 4294