Ascending Combinatorial Auctions with Risk Averse Bidders

Ascending combinatorial auctions are being used in an increasing number of spectrum sales worldwide, as well as in other multi-item markets in procurement and logistics. Much research has focused on pricing and payment rules in such ascending auctions. However, recent game-theoretical research has shown that such auctions can even lead to inefficient perfect Bayesian equilibria with risk-neutral bidders. There is a fundamental free-rider problem without a simple solution, raising the question whether ascending combinatorial auctions can be expected to be efficient in the field. Risk aversion is arguably a significant driver of bidding behavior in high-stakes auctions. We analyze the impact of risk aversion on equilibrium bidding strategies and efficiency in a threshold problem with one global and several local bidders. Due to the underlying free-rider problem, the impact of risk-aversion on equilibrium bidding strategies of local bidders is not obvious. We characterize the necessary and sufficient conditions for the perfect Bayesian equilibria of the ascending auction mechanism to have the local bidders to drop at the reserve price. Interestingly, in spite of the free-riding opportunities of local bidders, risk-aversion reduces the scope of the non-bidding equilibrium. The results help explain the high efficiency of ascending combinatorial auctions observed in the lab.     

Experts and Amateurs: The Role of Experience in Internet Auctions

The use of auctions as a pricing mechanism has grown dramatically over the last few years. The introduction of electronic auctions has significantly widened the pool of consumers who participate in auctions and increased the number of companies attempting to sell their products in an auction format. Previous empirical research on auctions has focused almost exclusively on the behavior of professional bidders in high stakes common value auctions or the behavior of students in laboratory experiments. We collect data on a large number of electronic auctions, across four product categories, to explore the behavior of consumers bidding in a real marketplace. In particular, we focus on the role experience plays in their bidding behavior to uncover whether consumer learning drives the bidding process towards outcomes described in the theoretical literature on auctions. We find that experience does indeed lead to behavior which is more consistent with theory although the proportion of experienced bidders who behave in a manner inconsistent with theory remains quite large.     

Auction Fever! How Time Pressure and Social Competition Affect Bidders’ Arousal and Bids in Retail Auctions

Auction sites on the Internet frequently put bidders under time pressure or highlight the social competition that is inherent to auctions. Both aspects are believed to elicit an exciting shopping experience, which may culminate in auction fever. In two laboratory experiments, we investigate the process of auction fever in retail auctions and demonstrate when and how auction fever affects bidding behavior. In contrast to previous studies, we employ physiological measurements as an objective and continuous assessment of bidders’ arousal in addition to a subjective assessment of bidders’ emotions through psychometric scales. Moreover, we explicitly study the interaction of time pressure and social competition on arousal and bids. We find that bidders’ arousal is increased in high time pressure auctions and that this leads to higher bids in ascending auctions—but only when bidders compete with human opponents. Thus, social competition is the actual driver underlying the auction fever phenomenon. Furthermore, we show that the “joy of winning” is significantly stronger than the “frustration of losing” in ascending auctions. Finally, we discuss the implications of our findings for the design of retail auctions.     

Strategic Bidding for Multiple Units in Simultaneous and Sequential Auctions

A buyer in an electronic marketplace may be interested in buying a bundle of items, where any one item in the bundle may not be of particular interest. The emergence of online auctions allow such users to obtain bundles by bidding on different simultaneous or sequentially run auctions. Because the number of auctions and the number of combinations to form the bundles may be large, the bundle bidding problem becomes intractable and the user is likely to make sub-optimal decision given time constraints and information overload. We believe that an automated agent that takes user preferences and budgetary constraints and can strategically bid on behalf of a user can significantly enhance user profit and satisfaction. Our first step to developing such an agent is to consider bundles containing many units of a single item to be bought from auctions that sell only multiple units of one item type. We assume that users obtain goods over several days. Expectations of auctions and their outcome in the future allow the agent to bid strategically on currently open auctions. We present an expected utility based strategy to decide how many items to bid for in the current auctions, and the maximum price to bid for each item. We evaluate our proposed strategy in different configurations by varying the number of items sold per auction, number of concurrently running auctions, expected closing prices, etc. We simulate several multiple unit English auctions per day, over multiple days, where most of the bidders bid their true utilities drawn from a distribution. The strategic bidding agent has knowledge of this distribution and uses it to determine its bids. A strategic agent who looks farther ahead into the future produces larger returns when there are few strategic bidders. We also evaluate the effect of risk attitudes on the relative performance of the bidders.     

The impact of jump bidding in online auctions

This paper reports findings of two field studies, conducted on a local online auction website, that compare bidding strategies in charity and non-charity auctions, focusing on the extent of jump bidding at different stages of auctions. Results indicate that jump bidding is negatively correlated with bidder entry and positively associated with ending prices. These correlations are greatest during the beginning stage of auctions and are substantially larger for charity auctions than for non-charity auctions. Additionally, early-stage jump bidding occurred more often in charity auctions (consistent with bidders trying to drive up prices in charity auctions), ending-stage jump bidding was more frequent in non-charity auctions (possibly used strategically to win the auction). Further, frivolous products tended to sell at a higher proportion of retail value in charity auctions, providing a replication of the results of previous researchers but in a field setting.     

Impact of Reputation and Promotion on Internet Auction Outcomes: Finnish Evidence

The purpose of this article is to explore the impact of seller’s reputation and promotional methods on auction outcomes in the Finnish online auction website, Huuto.net. Multiple linear and logistic regression analyses are used to test a set of hypotheses. The dataset consists of 227 auctions of iPhone 4S 16 GB mobile phones posted for auction by 138 individual sellers. The main finding is that sellers who have acquired a free identification from Huuto.net achieve a hefty increase in the final sales price. Sellers who have not established an online reputation achieve considerably lower closing prices at auction. An increase in negative feedback points reduces the final sales price. Purchasing display-enhancing promotional options does not increase the price but may improve probability of sale. Establishing reputation, avoiding negative feedback, and acquiring identification pay off. The promotional options associated with fonts and colors are not worth the cost.     

Effect of Buyer and Seller Experience on Buy It Now Pricing

ABSTRACT

Although auctions have been around for centuries, online auctions are still a relatively new phenomenon. This paper examines the phenomenon of online auctions, specifically on a pricing option known as “Buy It Now.” With this option, a buyer can purchase merchandise immediately at a stated price and truncate the auction process. Auction items sold with a Buy It Now price tend to be at a higher price than the high bid price for an identical item sold through an ascending-bid auction. In addition, Buy It Now prices tend to attract risk averse bidders while high bidders of ascending-bid auctions tend to be less risk averse or risk neutral bidders. On the other hand, we found more experienced sellers sell their items with a Buy It Now price while less experienced sellers sell their items through an ascending-bid process. Thus, experience and risk are factors in choosing a Buy It Now price for the seller and buyer.     

Empirical Testing of the Reference-Price Effect of Buy-Now Prices in Internet Auctions

Retailers selling items through Internet auctions frequently use buy-now prices (BNPs), which allow the immediate selling of an item to consumers at a fixed price. Previous research has proposed several theories of the usage of BNPs by bidders. We study the usage of BNPs from a seller's point of view. We propose that a retailer may use BNPs as external reference prices, influencing bidders’ valuations in Internet auctions. We focus on the effect of BNPs on bidders’ willingness to pay (WTP) and study under what conditions a BNP can be effectively used as an external reference price. Results of two empirical studies clearly indicate that BNPs have a reference-price effect. In addition, we find that this effect is moderated by (1) the difficulty of value assessment and (2) product value.     

The influence of seller strategy on the winning price in online auctions: A moderated mediation model

This paper examines the impact of seller strategy on winning prices in online auctions. In our conceptual model, three strategic choices made by the seller - minimum opening price, auction length, and use of a hidden reserve price - are mediated by the number of bids placed during the auction and moderated by product type. Our tests analyze eBay auction data for four consumer products through two matched studies (two products per study). In particular, we compare products for which value is easily determined with those for which value is less clear. Overall, we find strong evidence of the effects of minimum opening price and hidden reserve prices on final winning prices. The impact of auction length on winning price is less clear. In general, our tests support the idea that potential buyers rely more on signals such as opening price and reserve price for products for which reference prices are less available.     

Bidder motives in cause-related auctions

We study cause-related auctions where a percentage of the dynamically determined purchase price of an item is donated to charity. Little is known about the effectiveness of such auctions. Bidders who value donations to charity have an incentive to bid more aggressively in such auctions. Regardless of whether they win or not, these bidders can significantly affect prices. The purpose of this paper is to study bidders' willingness to pay a premium in charity auctions and the drivers that affect the charity premium. We use a carefully designed field experiment involving simultaneous pairs of auctions that are identical in all respects but percentage of the proceeds donated to charity. This design gives us the ability to look at bidder choice among auctions based on charitable considerations. We use a mixture model approach to allow for different types of individual preferences. We find that individuals fall into three segments: two altruistic segments and a selfish segment. The altruistic segments, which drive up the charity premium, can be classified as warm glow bidders who derive pleasure from the act of giving and other-regarding bidders who give for selfless reasons. Results show that the difference in donation percentages is the major factor influencing the charitable premium. However, bidders differ considerably in their responses to donation percentages. While other-regarding bidders tend to seek auctions where a greater percentage of revenue is donated to charity, warm glow bidders only contribute when the charity premium is sufficiently low. Thus, managers should focus their marketing efforts on appealing to these different segments, depending on the percentage donated to charity.     

Adverse inclusion of asymmetric advertisers in position auctions

Product listing platforms commonly use generalized second-price auctions to select competing advertisers for limited ad positions. However, when advertisers are asymmetric, position auctions may confound the post-auction competition structure and thus endogenize the bidders’ values of the ad positions. We build an analytical model to examine the impact of position auctions on an asymmetric market structure, which consists of a mass marketer and two specialized advertisers of heterogeneous quality efficiencies. The advertisers bid for two ad slots and then compete for the market in price and quality. We find that the asymmetric market structure may increase the uncertainty of the auction outcomes, which then may induce the advertisers to underbid using a conservative strategy profile in the locally-envy free equilibrium. Consequently, the auction outcome may adversely include the less-efficient specialized advertiser. This result is stronger than the position paradox in the classic auction literature, as the advertiser with a competitive advantage may be driven out and obtain zero profit.     

A Transaction Utility Approach for Bidding in Second-Price Auctions

In both the Vickrey and eBay auctions, bidding the reservation price is the optimal strategy within the conventional utility framework. However, in practice, buyers tend to bid less than their reservation prices, and bid multiple times, thus increase their bids, in the course of an auction. In this paper, we show that both underbidding and multiple bidding behaviors can be consistent with utility maximization, if buyer's utility incorporates a transaction utility (reference price dependent) component. Transaction utility is based on the difference between the buyer's reference price and actual price paid; it captures the perceived value of the deal. More specifically, we show that the optimal bid is lower than the reservation price, but higher than the reference price. Furthermore, buyer may re-bid (above the prior optimal level) if the reference price is revised upon observing a higher current price.     

Auctioning countermeasures in the WTO

We offer a first formal analysis of auctioning retaliation rights within the WTO. We show that the auctions exhibit externalities among bidders, and we characterize equilibrium bidder behavior under alternative auction formats. If the violating country is prevented from bidding to retire the right of retaliation against it, then the possibility of “auction failure” arises, whereby no bids are made despite positive valuation by bidders. If the violating country is instead permitted to bid, then auction failure is precluded, and indeed the right of retaliation is always retired. We evaluate these different auction formats from normative (revenue, compliance, efficiency) standpoints.     

The Effect of Social Cues on Sniping Behavior in Internet Auctions: Field Evidence and a Lab Experiment

This research explores how social cues presented in an online auction affect sniping behavior. Sniping is a strategy of placing a bid on an item in the very ending stages of an auction with a pre-determined ending time in an attempt to win the auction. Such a strategy conceals the intentions of the bidder until the last moments of the auction and minimizes the possibility of other opposing bidders submitting higher bids due to the short period of time left to respond. The research includes two field studies and a lab experiment indicating that sniping appears to be influenced by social factors, that is, when there are a greater number of bidders in the auction or the auction site provides social information about the bidders, the relative use of sniping increases. This research supports the perspective that bidders rely on others' bidding behavior and characteristics as an indication of the true value of the item on sale, and is one of the first studies in the literature which takes this perspective.     

(Un)expected Bidder Behavior in Spectrum Auctions: About Inconsistent Bidding and Its Impact on Efficiency in the Combinatorial Clock Auction

The combinatorial clock auction is a two-stage auction format, which has been used to sell spectrum licenses worldwide in the recent years. It draws on a number of elegant ideas inspired by economic theory. A revealed preference activity rule should provide incentives to bid straightforward, i.e., consistent with the bidders’ valuations on a payoff-maximizing package, in each round of the clock phase. A second-price rule should set incentives to bid truthfully in both phases. If bidders respond to these incentives and bid straightforward in the clock phase and truthful in the second sealed-bid stage, then the auction is fully efficient. Unfortunately, bidders might neither bid straightforward in the clock phase nor truthful on all packages in the second sealed-bid stage due to strategic reasons or practical limitations. We introduce metrics based on Afriat’s Efficiency Index to analyze straightforward bidding and report on empirical data from the lab and from the field in the British 4G auction in 2013 and the Canadian 700 MHz auction in 2014, where the bids were made public. The data provides evidence that bidders deviate significantly from straightforward bidding in the clock phase, which can restrict the bids they can submit in the supplementary phase. We show that such restrictions can have a significant negative impact on efficiency and revenue.     

To Discount or Not to Discount: An Assessment of Perceptions,Beliefs, and Intentions to Use Electronic Auctions with Discounts

In the digital economy, electronic auction systems are becoming more prevalent in facilitating the transactions between buyers and sellers. Auction websites, such as eBay and Amazon, as well as more sophisticated platforms, such as Moai and FrictionlessCommerce have increased transaction volume by offering tailored auction protocols to specific customer groups. meet2trade is a generic electronic market platform that supports various auction mechanisms. This study examines the impact of a discount in a second-price, sealed-bid mechanism on bidding behavior and market outcomes. Emphasis is thereby placed on bidders’ system-based perceptions, beliefs about usage and institutional-based trust, and intention to use such an auction. Ninety students were recruited to participate in an experiment held at a Western European university. The experiment observed user behavior in second-price auctions with and without a discount. The results demonstrate that although discounts do affect bidding behavior and economic outcomes, they do not influence bidder’s intentions to use such auction mechanisms. Instead, we found that intention to use is influenced by institutional and usage beliefs that are shaped by system-based perceptions, which in turn provide specific advice to market engineers on the technical aspects influencing system adoption.     

Economics, Psychology, and Social Dynamics of Consumer Bidding in Auctions

With increasing numbers of consumers in auction marketplaces, we highlight some recent approaches that bring additional economic, social, and psychological factors to bear on existing economic theory to better understand and explain consumers' behavior in auctions. We also highlight specific research streams that could contribute towards enriching existing economic models of bidding behavior in emerging market mechanisms. This paper is based on the special session at the 6th Triennial Invitational Choice Symposium, University of Colorado Boulder, June 2004 (co-chaired by the first two authors).     

Traders’ Subjective Appraisals: Comparison of Negotiations and Auctions

ABSTRACT

The assessments of business trade often involve economic and relational concerns. They may become more challenging when our understanding of the impacts of trading mechanisms is still limited. The current experimental study compares two generic trading mechanisms, namely, multibilateral multi-issue negotiations and multicriteria auctions. By examining economic measures and subjective appraisals in controlled exchange episodes, the study shows some subtle relationships between mechanism use, substantive outcomes, and subjective appraisals. While use of negotiations versus auctions did not reveal significant differences on economic measures, traders are strongly influenced by the gain-or-loss contingency. When they win a contract, their subjective appraisals are heavily influenced by their achieved substantive outcomes. When they do not win a contract, they feel auctions are better than negotiations. The results confirm the assessments of business trade that rely solely on substantive measures are not sufficient.     

Reducing information asymmetry in the auctioning of non-perishable experience goods: The case of online wine auctions

We highlight the importance of reducing the perceived risk associated with information asymmetry for experience goods. We analyse a major online non-perishable experience good, wine, from the seller's perspective. The mechanism for lowering information asymmetry is the verification service offered by the auctioneer. By focusing on unsold items/lots, the wine and auction characteristics affecting the probability of a sale are identified. Results show that the verification of the wine's provenance increases the probability of sale by 5.7 percent and leads to an expected increase of 5.1 percent in the auction price. When both effects are combined, the increase in the expected revenue of the seller is 7.3 percent. We test and find no evidence of selection bias. Given the heterogeneity in wine prices, a quantile regression analysis shows how the results differ for high-priced wines compared to lower priced wines. Results highlight how the mechanisms to lower the degree of information asymmetry work both in attracting bidders to online auctions and encouraging bidders to submit higher bids.