Peer effects in learning HIV results

How do neighbors positively or negatively influence individuals living in rural Malawi to learn their HIV results? Using data of location of homes and distance to neighbors, we measure the social network effects of neighbors' learning their HIV results on individuals own learning. Using the fact that neighbors were randomly offered monetary incentives of varying amounts to learn their HIV results, we find positive effects of neighbors attending clinics on others living nearby: a 10 percentage point increase of the percentage of neighbors (approximately 2.4 individuals) learning their HIV results increases the probability of learning HIV results by 1.1 percentage points. The strongest network effects are among closest neighbors; we find no effect among religious social networks. We also find a negative interaction between direct cash incentives and peers: the effect of peers doubles among those who were not offered any individual financial incentive to learn their HIV results.     

On the informational inefficiency of discriminatory price auctions

We analyze bidding behavior in large discriminatory-price auctions in a common value setting where the number of objects is a non-trivial proportion of the number of bidders. We show that the average price paid in the auction is biased downward from the expected value of the objects, even in the competitive limit. We show that conditional on a signal that falls below a threshold, a bidder bids no more than the expected value of an object conditional on the signal and winning; while conditional on any signal that lies above the threshold the bid is strictly lower than the expected value conditional on the signal and winning.     

CHARITY AUCTIONS*

In a charity auction the public‐goods nature of auction revenue affects bidding incentives. We compare equilibrium bidding and revenue in first‐price, second‐price, and all‐pay charity auctions. Bidding revenue typically varies by selling format. First‐price auctions are less lucrative than second‐price and all‐pay auctions, and with sufficiently many bidders the all‐pay auction has the highest bidding revenue. However, revenue equivalence applies when the auctioneer can set a reserve price and fees plus threaten to cancel the auction. If the auctioneer cannot threaten cancellation, a reserve and bidding fee can augment revenue but again revenue varies by auction format     

EXPERIMENTAL EVIDENCE ON ENGLISH AUCTIONS: ORAL OUTCRY VERSUS CLOCK

This paper tests experimentally, in a common value setting, the equivalence between the Japanese English auction (or clock auction) and an oral outcry auction where bidders are allowed to call their own bids. We find that (i) bidding behaviour is different in each type of auction, but also that (ii) this difference in bidding behaviour does not affect significantly the auction prices. This lends some support to the equivalence between these two types of auction. The winner's curse is present: overbidding led to higher than expected prices (under Nash bidding strategies) in both types of auction. Although interesting and encouraging, the results clearly indicate that further research is necessary, particularly with a modified experimental design.     

A robust algorithm for parameter estimation in smooth transition autoregressive models

This paper considers whether earned wealth affects bidding behavior in an induced-value second-price auction. We find people bid more sincerely in the auction with earned wealth given monetary incentives; earned wealth did not induce sincere bidding in hypothetical auctions.     

Demand reduction and preemptive bidding in multi-unit license auctions

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.     

On ascending Vickrey auctions for heterogeneous objects

We construct an ascending auction for heterogeneous objects by applying a primal-dual algorithm to a linear program that represents the efficient-allocation problem for this setting. The auction assigns personalized prices to bundles, and asks bidders to report their preferred bundles in each round. A bidder's prices are increased when he belongs to a “minimally undersupplied” set of bidders. This concept generalizes the notion of “overdemanded” sets of objects introduced by Demange, Gale, and Sotomayor for the one-to-one assignment problem. Under a submodularity condition, the auction implements the Vickrey-Clarke-Groves outcome; we show that this type of condition is somewhat necessary to do so. When classifying the ascending-auction literature in terms of their underlying algorithms, our auction fills a gap in that literature. We relate our results to various ascending auctions in the literature.     

Asymmetric information about rivals'' types in standard auctions

We study auctions in which bidders may know the types of some rival bidders but not others. This asymmetry in bidders' knowledge about rivals' types has different effects on the two standard auction formats. In a second-price auction, it is weakly dominant to bid one's valuation, so the knowledge of rivals' types has no effect, and the good is allocated efficiently. In a first-price auction, bidders refine their bidding strategies based on their knowledge of rivals' types, which yields an inefficient allocation. We show that the inefficient allocation in the first-price auction translates into a poor revenue performance. Given a standard regularity condition, the seller earns higher expected revenue from the second-price auction than from the first-price auction, whereas the bidders are better off from the latter.     

ON DETAIL‐FREE MECHANISM DESIGN AND RATIONALITY*

Mechanism design theory has been criticized, because mechanisms depend on the detail of specification and agents’ behaviour relies on strong rationality assumptions. Hence the study of “detail‐free” mechanism design with weak rationality is important as a practical theory. This paper emphasizes that, even if we confine our attention to detail‐free mechanisms with weak rationality, there exists plenty of scope for the development of new and significant ideas. I describe my recent work along these lines, and argue that stochastic decisions work in large double auction environments, and that moral preferences improve the implementability of social choice functions.     

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.     

Individual behavior of first-price auctions: The importance of information feedback in computerized experimental markets

This article reports the results of an individual choice experiment designed to test the Nash equilibrium predictions of the first-price sealed-bid auction. A subject faced in 100 auctions always the same resale value and competed with computer-simulated bids. The design used between-subjects variation and involved information feedback as the treatment variable. Earlier experimental work on first price auctions has frequently reported an overbidding relative to the risk neutral Nash equilibrium. Our data provide evidence that overbidding can be fostered by the standard information feedback in auction experiments, which, after each auction, reveals the winning bid only. By means of learning direction theory we explain the individual bidding dynamics in our experiment. Finally we apply impulse balance theory and make long run predictions of individual bidding behavior.     

Charity auctions with multiple goods: Bidding behavior and revenue

In a charity auction with multiple goods, we show that the highest-losing bid uniform price auction revenue dominates its lowest-winning bid counterpart. Only in the highest-losing bid uniform price auction is bidding independent of the number of goods and players and revenue increasing in the number of goods.     

An inter-temporal general equilibrium analysis of the Australian age pension means test

The Australian age pension is somewhat unusual among developed countries in that it is means tested against both the claimant’s income and assets. While means testing of age pensions facilitates the aims of directing public pensions to those senior individuals most in need and of containing pension expenditures by governments, it also has the effect of changing the incentives of individuals to work and save. This paper examines the implications of the Australian means tested age pension for incentives of individuals to save and work, for government financial commitments and for the welfare of individuals. To this end, we develop an overlapping generations model of the Australian economy that incorporates the essential features of the Australian pension, superannuation and taxation policy settings and use it to explore the implications of several hypothetical policy changes that relax the means test of the age pension. Our results confirm that the existing means-tested, age pension represents a disincentive for some older Australians to work.     

Non-bidding equilibrium in an ascending core-selecting auction

This paper investigates the perfect Bayesian equilibrium in an ascending-price core-selecting auction, which is recently used in some countries? spectrum license auctions. We suppose that there are two identical items, two small bidders, and one large bidder. The small bidders demand only one unit of the item, whereas the large bidder wants both units. Package bidding ensures that the large bidder faces no exposure problem and behaves truthfully. However, one of the small bidders stops bidding at the beginning in the equilibrium. Although small bidders generally face the free-rider problem and have incentives to underbid, once a bidder is the only small one remaining, he bids truthfully. Stopping early induces the remaining bidder to behave truthfully. Hence, each small bidder wants to be the first to stop bidding. The free-rider problem is considerably mitigated when there are many small bidders.     

PORTFOLIO ALLOCATION IN THE FACE OF A MEANS‐TESTED PUBLIC PENSION

We investigate whether households adjust their asset portfolios just prior to retirement in ways that are consistent with maximizing eligibility for a means‐tested public pension. We utilize detailed micro data for a nationally‐representative sample of Australian households to estimate a system of asset equations which are constrained to add up to net worth. Our results provide little evidence that healthy households or couples are responding to the incentives embedded in the means tests determining pension eligibility by reallocating assets. While there are some differences in asset portfolios associated with having an income near the income threshold, being of pensionable age, and being in poor health, these differences are often only marginally significant and are not clearly consistent with the incentives inherent in the Australian age pension eligibility rules. Any behavioral response to the incentives inherent in the age‐pension means test appears to be predominately concentrated among single pensioners who are in poor health.     

THE EFFECTS OF FEEDBACK ON SELF‐ASSESSMENT

It is a well‐known phenomenon that people have difficulties in assessing their ability correctly. Often they overestimate their (relative) abilities. We conduct an experiment to test whether the self‐assessment of individuals improves when they receive feedback and there are incentives to make a correct self‐assessment. We investigate the subjects' reactions to feedback in several subsequent rounds to see not only if, but also when and how they react. Our main finding is that feedback influences subjects' decisions and can improve their overall self‐assessment. The effects, however, depend on the kind of feedback. Furthermore, we observe differences in the reactions of subjects (e.g., to what extent they follow feedback), the robustness of their belief about their relative ability, and how they process feedback.     

Information acquisition in auctions: Sealed bids vs. open bids

This paper studies the incentives of a bidder to acquire information in an auction when her information acquisition decision is observed by the other bidders before bidding. Our results show that the sealed bid (second price) auction may induce more information acquisition about a common component of the value than the open (English) auction but less about the private component of the value. Moreover, we show that more information about the private value and less information about the common value may improve efficiency and revenue. Consequently, our results suggest new arguments in favor of the open auction.     

Commitment in sequential auctioning: advance listings and threshold prices

This paper models sequential auctioning of two perfect substitutes by a strategic seller, who learns about demand from the first-auction price. The seller holds the second auction only when the remaining demand is strong enough to cover her opportunity cost. Bidding in anticipation of such a contingent future auction is characterized, including a sufficient condition for existence of an invertible (increasing symmetric pure-strategy) bidding equilibrium that facilitates the seller’s learning. A unique invertible bidding equilibrium exists for the Dutch auction format, but only when the second auction is sufficiently discounted by the bidders. In the equilibrium, high-valuation bidders shade their bids down as if the second auction were guaranteed. To counter such strategic bidding, the seller would value ex-ante commitment to hold the second auction less often. Three forms of such commitment are analyzed: commitment to list future auctions in advance, commitment to not hold the second auction unless the first price exceeds a publicly announced threshold, and commitment to a reserve-price in the second auction. I would like to thank Georgios Katsenos, Thomas Jeitschko, Miguel Villas-Boas, George Deltas, and an anonymous referee for thorough and insightful feedback.     

Endogenous entry and self-selection in private value auctions: An experimental study

This paper presents the results of an experimental study of endogenous entry in first-price independent private value auctions. N potential bidders simultaneously decide whether to participate in an auction or receive a known outside option. In the second stage, entrants submit bids after learning their own private values and the number of entrants. An equilibrium model of heterogeneous risk averse bidders implies a self-selection effect, where bidding in the auction is lower with endogenous entry because only less risk averse bidders enter. This effect is confirmed by the experiment. We also observe excessive entry relative to the theoretical model.     

A Study of Collusion in First-Price Auctions

This paper examines the bidding for school milk contracts in Florida and Texas during the 1980s. In both states firms were convicted of bid-rigging. The data and legal evidence suggest that the cartels in the two states allocate contracts in different ways: One cartel divides the market among members, while the other cartel also uses side payments to compensate members for refraining from bidding. We show that both forms of cartel agreements are almost optimal, provided the number of contracts is sufficiently large.
In the auction the cartel bidder may face competition from non-cartel bidders. The presence of an optimal cartel induces an asymmetry in the auction. The selected cartel bidder is bidding as a representative of a group and has on average a lower cost than a non-cartel bidder. The data support the predicted equilibrium bidding behaviour in asymmetric auctions in accordance with optimal cartels.