Truthful approximation mechanisms for restricted combinatorial auctions

When attempting to design a truthful mechanism for a computationally hard problem such as combinatorial auctions, one is faced with the problem that most efficiently computable heuristics can not be embedded in any truthful mechanism (e.g. VCG-like payment rules will not ensure truthfulness).We develop a set of techniques that allow constructing efficiently computable truthful mechanisms for combinatorial auctions in the special case where each bidder desires a specific known subset of items and only the valuation is unknown by the mechanism (the single parameter case). For this case we extend the work of Lehmann, O'Callaghan, and Shoham, who presented greedy heuristics. We show how to use If-Then-Else constructs, perform a partial search, and use the LP relaxation. We apply these techniques for several canonical types of combinatorial auctions, obtaining truthful mechanisms with provable approximation ratios.     

Vickrey auctions with reserve pricing

Summary. We generalize the Vickrey auction to allow for reserve pricing in a multi-unit auction with interdependent values. In the Vickrey auction with reserve pricing, the seller determines the quantity to be made available as a function of the bidders' reports of private information, and then efficiently allocates this quantity among the bidders. Truthful bidding is a dominant strategy with private values and an ex post equilibrium with interdependent values. If the auction is followed by resale, then truthful bidding remains an equilibrium in the auction-plus-resale game. In settings with perfect resale, the Vickrey auction with reserve pricing maximizes seller revenues.Received: 31 December 2002, Revised: 5 May 2003, JEL Classification Numbers: D44, C78, D82.Correspondence to: Lawrence M. AusubelThe authors gratefully acknowledge the generous support of National Science Foundation Grants SES-97-31025, SES-01-12906 and IIS-02-05489. We appreciate valuable comments from Ilya Segal. Special thanks go to Mordecai Kurz, who served as Larry's dissertation advisor and who introduced both authors to the economics profession back at IMSSS at Stanford. Congratulations and best wishes are extended to Mordecai and his family on the happy occasion of the publication of Assets, Beliefs, and Equilibria in Economic Dynamics: Essays in Honor of Mordecai Kurz, in which this article also appears.     

Collusion in one-shot second-price auctions

Summary. Most of the literature on collusive behavior in auctions ignores two important issues that make collusion difficult to sustain at least in one-shot interactions: the detection of cheating and the verification of bids. Colluding bidders may deceive each other by using shill bidders. Also, if the identities of the bidders and their bids are not published then it would be difficult to verify the bid of a colluding bidder. This paper addresses these problems in one shot second price auctions where one bidder offers another bidder a side payment in exchange for not participating in the auction, while the number of other bidders is stochastic. In spite of the barriers to collusion mentioned above, a simple side payment mechanism which depends only on the auction price is introduced. It induces a successful collusion, eliminates the verification problem, provides no incentive for the use of shill bidders and guarantees that the proponent obtains ex-post non-negative payoff. The colluding bidders are ex-ante strictly better off compared with the competitive case, irrespective of their types.Received: 27 November 2002, Revised: 28 January 2005, JEL Classification Numbers: C72, D44, D82.Yair Tauman: Correspondence toWe would like to thank an anonymous referee for very valuable comments and suggestions that significantly improved the paper. We thank Shmuel Zamir for a helpful discussion.     

Second chance offers versus sequential auctions: theory and behavior

Second chance offers in online marketplaces involve a seller conducting an auction for a single object and then using information from the auction to offer a losing bidder a take-it-or-leave-it price for another unit. We theoretically and experimentally investigate this practice and compare it to two sequential auctions. We show that the equilibrium bidding strategy in the second chance offer mechanism only exists in mixed strategies, and we observe that this mechanism generates more profit for the auctioneer than two sequential auctions. We also observe virtually no rejections of profitable offers in the ultimatum bargaining stage.      

Competition in the economic crisis: Analysis of procurement auctions

We study the effects of the recent economic crisis on firms׳ bidding behavior and markups in sealed bid auctions. Using data from Austrian construction procurements, we estimate bidders׳ construction costs within a private value auction model. We find that markups of all bids submitted decrease by 1.5 percentage points in the recent economic crisis, markups of winning bids decrease by 3.3 percentage points. We also find that without the government stimulus package this decrease would have been larger. These two pieces of evidence point to pro-cyclical markups.     

Bundling decisions for selling multiple objects

Summary. Auctioneers often face the decision of whether to bundle two or more different objects before selling them. Under a Vickrey auction (or any other revenue equivalent auction form) there is a unique critical number for each pair of objects such that when the number of bidders is fewer than that critical number the seller strictly prefers a bundled sale and when there are more bidders the seller prefers unbundled sales. This property holds even when the valuations for the objects are correlated for a given bidder. The results have been proved using a mathematical technique of quantiles that can be extremely useful for similar analysis. Received: November 5, 1996; revised version: January 21, 1998     

A study of zero-out auctions: testbed experiments of a process of allocating private rights to the use of public property

Summary This paper applies an experimental testbed methodology to the evaluation of a proposed mechanism for allocating the right to land at the New York airports. The mechanism is called a zero-out auction because it is supposed to allocate the rights efficiently like an auction while leaving all of the consumer's surplus with the buyers (as opposed to allocating some to the seller as would be the case with an ordinary auction). A new behavioral hypothesis is introduced to account for limited rationality of individuals and unusual behaviors of the process. The axiom, called theunbiased expectations hypothesis, does a good job of modeling individual behavior in the context of a game model.We acknowledge the financial support of the National Science Foundation and the Caltech Laboratory for Experimental Economics and Political Science. Comments by David Grether, John Ledyard, Michael Levine, Jennifer Reinganum, and Richard Sutch have been very helpful.     

Determining damages from the operation of bidding rings: An analysis of the post-auction `knockout' sale

Summary. This paper studies ‘knockout’ auctions, typically organized by bidding rings, in which the winning bidder makes side-payments to all losing bidders. These side-payments provide an incentive for the ring members to bid higher than they would have in an identical public auction. As a consequence, neither the realized price nor the total payments of the winner are unbiased estimates of the item's price in the absence of collusion. This paper evaluates the extent of this overestimate in the independent private values case, for first and second price post-auction knockouts. Bids are not independent of the sharing rule but transfers from the winning bidder are. Further, bidder payoffs are independent of both the auction format and the sharing rule. The “overbidding” in the knockout is increasing with the dispersion of bidder valuations and of significant empirical relevance. This paper's results can be used to obtain an unbiased assessment of the damages inflicted on the seller. Received: May 1, 1996; revised version: September 7, 2000     

Auctions with endogenous valuations: the snowball effect revisited

Summary. This paper looks at the determination of ownership of capacity when there are two ex-ante symmetric agents bidding for many units of capacity which are sold sequentially. It is shown that convexity of payoffs in the final stage of the game is sufficient to ensure monopolization of capacity, but that increasing returns to scale are not sufficient to ensure monopolization. Received: March 14, 1997; revised version: December 1, 1997     

Priced on the note: the case of Japanese IPOs

ABSTRACT

This article examines the pricing of Japanese IPOs: 54.26% are priced in 1,000 Japanese yen increments (The Japanese yen (JPY) has denominations of banknotes and coins. Banknotes are in 1,000, 2,000, 5,000, and 10,000-yen. Coins are in 1, 5, 10, 50, 100, and 500-yen. One thousand banknotes are similar to US $10 dollars. Coins are considered as changes in Japan.) (note-ending IPOs), an economically large increment on a per-share basis that is equivalent to 10 US dollar increments assuming an exchange rate of 1 US dollar to 100 Japanese yen. The number of note-ending IPOs increases with price levels and pricing uncertainty, supporting the negotiation hypothesis. Note-ending IPOs are associated with higher volatility, higher underwriters’ fees, wider filing price range, smaller deal size, shorter firm age, and lower underwriter reputation. Price clustering contributes to IPO underpricing. The initial returns are 60.44% higher for note-ending relative to coin-ending IPOs. These results shed light on the pricing of Japanese IPOs due to negotiations and on investment opportunities with note-ending IPOs.     

The law of small numbers: investigating the benefits of restricted auctions for public procurement

A commonly accepted view in the academic literature is that dispensing with competition may only be beneficial when tendering complex contracts. However, restricted auctions are frequently used among EU member states to procure small contracts. In this article, we investigate this paradox. Using an original data set of 180 contracts used by a local public buyer of social housing between 2006 and 2009, we show that limiting competition may enable economies to be made on transaction costs while the most efficient bidders still come forward, and that abuses such as corruption or favouritism do not result. To our knowledge, this article is the first to shed light on the advantages of using restricted auctions when tendering small simple contracts.     

A multiple perspectives view of the market case for green energy

This paper presents an exploratory evaluation of the market case for green energy. These energy sources are widely considered to have less of an ecological impact than conventional energy sources. The case for green energy is viewed from the multiple perspectives TOP (technical, organizational, personal) framework. The green energy technologies will need to meet certain technical, organizational and personal criteria and resolve key issues in order to address the barriers to market adoption. The multiple perspectives approach facilitates the evaluation of green-energy alternatives as potential new products which would enable organizations and individuals to meet both economic and green criteria that impact customer value creation. Given the present trends of increasing energy use and requirements to minimize environmental impact, green energy adoption may become a key element of strategies to ensure long-term economic growth.     

Global warming: Efficient policies in the case of multiple pollutants

This article investigates efficient policies against global warming in the case of multiple greenhouse gases. In a dynamic optimization model conditions for an efficient combination of abatement activities are derived. It is shown how this solution can be decentralised by a system of emission charges. Since the determination of the charge rates should be based on a long time horizon, the impact of sequential planning methods is explored. The parameters of the model are specified with respect to the main greenhouse gases (carbon dioxide, methane, nitrous oxide, chlorofluorocarbons) and a scenario for an efficient charge system is calculated. For the main emission sources the tax base and the likely range of tax rates is derived. The results illustrate that efficient policy measures against global warming will not only affect the use of fossil fuels but will also impose a considerable burden on modern agriculture specialising in livestock and in intensive farming techniques.     

Sensitive products in the Doha negotiations: The case of European and Japanese market access

Given the highly concentrated distribution of agricultural protection, allowing in the negotiations too many exceptions through sensitive products puts at risk the objectives of World Trade Organization. This issue is difficult to analyze with the commonly used applied trade models, because they represent trade flows at an aggregate level, while sensitive products are picked at the product level and their protection, under the form of tariff-rate quotas, is contingent on the level of imports. This paper assesses the effect of these exceptions, based on the case of agricultural trade protection in Europe and Japan, two countries where tariff dismantling in the agricultural sector is a particularly sensitive issue. Since agricultural border protection is heterogeneous, we avoid aggregation bias by extending a multi-country computable general equilibrium model to the product level. This allows us to represent trade policies explicitly and to account for their interdependencies. The results suggest that consideration of sensitive products strongly limits the potential gains from a possible agriculture agreement at Doha. Moreover, there is no aggregate trade-off between decreasing tariffs and increasing/opening quotas. To achieve “substantial” market access improvements in the agricultural sector, the objective should be most favored nation tariff reduction.     

Cycles and multiple equilibria in the market for durable lemons

Summary. The paper investigates the nature of market failure in a dynamic version of Akerlof (1970) where identical cohorts of a durable good enter the market over time. In the dynamic model, equilibria with qualitatively different properties emerge. Typically, in equilibria of the dynamic model, sellers with higher quality wait in order to sell and wait more than sellers of lower quality. The main result is that for any distribution of quality there exist an infinite number of cyclical equilibria where all goods are traded within a certain number of periods after entering the market. Received: December 21, 2000; revised version: September 5, 2001     

Using observational analysis of multiple sclerosis relapse to design outcomes-based contracts for disease-modifying drugs: a feasibility assessment

Abstract

Objective:

To assess predictors and costs of multiple sclerosis (MS) relapse, a potential outcome measure in payer-manufacturer risk-sharing agreements for disease-modifying drugs (DMDs).

Methods:

A retrospective cohort analysis of medical/pharmacy claims was used. Study patients had ≥1 DMD (interferon beta, glatiramer, natalizumab) claim, without DMD claims in a 6-month pre-period before DMD initiation; were aged 18–64 years and continuously enrolled from the pre-period through a 24-month post-period; and had ≥2 MS medical claims during the 30-month study period. Post-period relapse cohorts included: (1) severe (hospitalization with MS diagnosis); (2) moderate (outpatient services including intravenous methylprednisolone); and (3) none. Poisson regression modeled severe relapse frequency, logistic regression modeled ≥1 severe relapse, and generalized linear modeling predicted healthcare costs. Tested predictors included demographics, insurance type, index DMD, pre-period health status, and DMD medication possession ratio (MPR).

Results:

Severe relapse was experienced by 14.5% and moderate relapse by 13.8% of 2291 patients. In logistic regression, severe relapse was predicted by plan type; age (odds ratio [OR]?=?1.018, 95% confidence interval [CI]?=?1.005–1.031); pre-period Charlson Comorbidity Index (OR?=?1.307, 95% CI?=?1.166–1.464); pre-period proxy measure indicating impaired activities of daily living (OR?=?1.470, 95% CI?=?1.134–1.905); pre-period MS hospitalization (OR?=?2.174, 95% CI?=?1.537–3.074); and DMD non-adherence (MPR OR?=?0.101, 95% CI?=?0.068–0.151). Poisson regression results were similar. Predicted mean [standard deviation] all-cause healthcare expenditures were tripled for patients with severe compared with moderate relapse ($48,173 [$8665] and $13,334 [$1929], respectively).

Limitations:

Commercially insured patients from a single payer; use may have been inconsistent with approved indications; proxy relapse measure may have misclassified patients.

Conclusions:

Severe MS relapses requiring hospitalization, although affecting less than 15% of patients initiating DMD treatment, are associated with high medical costs. The only actionable predictor of severe relapse identified in observational analysis was MPR, raising questions about the feasibility of using observational data to guide outcomes-based contracting.     

Farming system modelling for agri-environmental policy design: The case of a spatially non-aggregated allocation of conservation measures

This paper addresses the issue of designing policies for habitat conservation on agricultural land. The case under study requires a non-aggregated spatial distribution of the fields to be enrolled in an agri-environmental programme. A spatially explicit mathematical programming farm-based model, which accounts for three spatial levels (field, farm and landscape), is coupled with a relevant spatial pattern index (the Ripley L-function) to analyse the design and implementation of an agri-environmental programme aimed to preserve the Tetrax tetrax in the Plaine de Niort, France. The model is run using a stylised map with heterogeneous soil types and both crop growing and mixed dairy farms. Results show that valuable insights into agri-environmental programme design are gained through a detailed representation of farming system management. The suitable, non-aggregated spatial pattern for T. tetrax conservation is more costly than less-suitable, more aggregated patterns, because it tends to require equal participation of all farms. The policy simulations reveal that the various spatial patterns can be obtained through relatively simple uniform contract structures. An effective contract structure entails a set of two degressive payments which encourages all farms to enrol at least a small share of their land in the program.     

Bounding the benefits of stochastic auditing: The case of risk-neutral agents

Summary. In the context of a costly-state-verification model with a risk-neutral agent having limited liability, it has been postulated that allowing stochastic auditing reduces the asymmetric information problem to a trivial one: i.e., the first best can be approached arbitrarily closely with feasible contracts. This paper proves the postulate to be false: the surplus from feasible contracts is bounded strictly below the first-best surplus level. The bound is straightforward to compute in examples. The paper thus removes a justification for the restriction to deterministic auditing commonly made in the literature. Received: July 18, 1997; revised version: February 23, 1998     

Taxation of multiple greenhouse gases and the effects on income distribution: A case study of the Netherlands

Current economic instruments aimed at climate change mitigation focus on CO₂ emissions only, but the Kyoto Protocol refers to other greenhouse gases (GHG) as well as CO₂. These are CH₄, N₂O, HFCs, PFCs and SF₆. Taxation of multiple greenhouse gases improves the cost-effectiveness of climate change mitigation. It is not yet clear, however, what the effect is of multigas taxation on the distribution of the tax burden across income groups. This paper examines and compares distributional effects of a CO₂ tax and a comprehensive tax that covers all six GHG of the Kyoto Protocol. The study concentrates on the Netherlands in the year 2000. We established tax rates on the basis of marginal abatement cost curves and the Dutch policy target. The distributional effects have been determined by means of environmentally extended input−output analysis and data on consumer expenditures. Our results show that taxation of multiple GHG improves not only the cost-effectiveness of climate change mitigation, but also distributes the tax burden more equally across income groups as compared to a CO₂ tax. These findings are relevant for the debate on the role of non-CO₂ GHG in climate change mitigation.