On an ad hoc test for order restricted multivariate normal means

Abstract

For several normal mean vectors restricted by a simple ordering with respect to a multivariate order, this article derives sufficient and necessary conditions for the restricted MLEs for both mean vectors and covariance matrix, and develops an ad hoc test. It establishes conditions for the bounds of the p-values. One example of such bound is given with some comments.     

The Organization of Supplier Networks: Effects of Delegation and Intermediation

In a one‐principal two‐agent model with adverse selection and collusion among agents, we show that delegating to one agent the right to subcontract with the other agent always earns lower profit for the principal compared with centralized contracting. Delegation to an intermediary is also not in the principal's interest if the agents supply substitutes. It can be beneficial if the agents produce complements and the intermediary is well informed.     

Behavior in Multi‐Unit Demand Auctions: Experiments with Uniform Price and Dynamic Vickrey Auctions

We experimentally investigate the sensitivity of bidders demanding multiple units of a homogeneous commodity to the demand reduction incentives inherent in uniform price auctions. There is substantial demand reduction in both sealed bid and ascending price clock auctions with feedback regarding rivals' drop‐out prices. Although both auctions have the same normal form representation, bidding is much closer to equilibrium in the ascending price auctions. We explore the behavioral process underlying these differences along with dynamic Vickrey auctions designed to eliminate the inefficiencies resulting from demand reduction in the uniform price auctions.     

Identification of Standard Auction Models

This paper presents new identification results for models of first–price, second–price, ascending (English), and descending (Dutch) auctions. We consider a general specification of the latent demand and information structure, nesting both private values and common values models, and allowing correlated types as well as ex ante asymmetry. We address identification of a series of nested models and derive testable restrictions enabling discrimination between models on the basis of observed data. The simplest model—symmetric independent private values—is nonparametrically identified even if only the transaction price from each auction is observed. For richer models, identification and testable restrictions may be obtained when additional information of one or more of the following types is available: (i) the identity of the winning bidder or other bidders; (ii) one or more bids in addition to the transaction price; (iii) exogenous variation in the number of bidders; (iv) bidder–specific covariates. While many private values (PV) models are nonparametrically identified and testable with commonly available data, identification of common values (CV) models requires stringent assumptions. Nonetheless, the PV model can be tested against the CV alternative, even when neither model is identified.     

All‐Pay Contests

This paper studies a class of games, “all‐pay contests,” which capture general asymmetries and sunk investments inherent in scenarios such as lobbying, competition for market power, labor‐market tournaments, and R&D races. Players compete for one of several identical prizes by choosing a score. Conditional on winning or losing, it is weakly better to do so with a lower score. This formulation allows for differing production technologies, costs of capital, prior investments, attitudes toward risk, and conditional and unconditional investments, among others. I provide a closed‐form formula for players' equilibrium payoffs and analyze player participation. A special case of contests is multiprize, complete‐information all‐pay auctions.     

On the Existence of Monotone Pure‐Strategy Equilibria in Bayesian Games

We generalize Athey's (2001) and McAdams' (2003) results on the existence of monotone pure‐strategy equilibria in Bayesian games. We allow action spaces to be compact locally complete metric semilattices and type spaces to be partially ordered probability spaces. Our proof is based on contractibility rather than convexity of best‐reply sets. Several examples illustrate the scope of the result, including new applications to multi‐unit auctions with risk‐averse bidders.     

固定价格与英式拍卖同时使用时顾客行为分析

很多网站采用在英式拍卖中加入固定价格选项的方式销售多件同类商品.我们证明了,在此规则下存在一个弱占优投标策略.若顾客对商品的估价低于固定价格,那么,当拍卖价格低于他的估价时,该顾客参与拍卖,且以自己的估价作为报价是他的弱占优投标策略;否则,当拍卖价格超过他的估价时,他退出拍卖.若顾客对商品的估价高于或等于固定价格,他会在参与拍卖和接受固定价格之间进行选择;若他参与拍卖,将固定价格作为报价是他的弱占优投标策略.我们发现,该顾客是选择参与拍卖、还是选择以固定价格购买主要依赖于顾客到达拍卖时距离拍卖结束的剩余时间.最后,通过算例,我们对影响顾客参与策略的因素进行了数值分析并得到了一些结论.     

Ad hoc网络稳定的蚁群多路由算法

针对Ad hoc网络路由协议中存在的路由老化和对拓扑变化适应性差的问题,提出了一种基于稳定拓扑和蚁群优化的多路由算法(SAMR),路径质量由路径的拓扑稳定度和时延来度量,并映射为蚁群信息素,利用蚁群优化进行路由的动态更新和维护,以避免路由老化。仿真表明,在动态环境下SAMR相比AODV能提高网络的吞吐量、降低传输时延。     

具有高投标成本的多属性逆向拍卖博弈模型

越来越多像GE这样的大型企业在利用多属性逆向拍卖选择新的供应商采购产品时,通常会设定较高的固定投标成本。针对此情况,建立了三阶段的非合作博弈模型,并利用求解子博弈纳什均衡策略的方法,推导出了供应商的最优投标价格。并得到以下两个主要结论:一是供应商的最优投标策略是按照生产产品真实的质量和交货期进行投标,且投标价格为最优投标价格;二是采购商的最优策略是选择投标价格最高的供应商作为拍卖获胜者,这一违反直觉的结论。这是合理的,因为投标价格最高的供应商也是类型最优的供应商,也即投标质量和投标交货期组合最优的供应商。最后,利用数值实验验证了模型的有效性,并显示出设定相对较高的固定投标成本对采购商来说是有利的。     

采购拍卖与谈判机制设计及其贝叶斯均衡策略

设计了一种先"拍卖"再"谈判"的两阶段采购机制,实现了更具分配效率且更符合实际的单物品采购运作。该机制设计的特色在于考虑到:采购业务中同时存在关于价格和质量的投标竞争与议价谈判,供应商与采购商在采购的不同阶段的私有信息披露问题,以及谈判阶段的时间成本和相应均衡策略问题。研究的基本结论是:在机制的拍卖阶段中,存在最佳近视反应意义下的招投标策略;机制的议价阶段在均衡路径上的分配结果,与买卖双方的真实价值具有重要的确定性关系;议价阶段实现了对拍卖阶段分配效率的改进,且买卖双方都存在关于质量和价格的贝叶斯纳什均衡议价策略与相关信念。