A general class of test statistics for Van Valen's Red Queen hypothesis

Van Valen's Red Queen hypothesis states that within a homogeneous taxonomic group the age is statistically independent of the rate of extinction. The case of the Red Queen hypothesis being addressed here is when the homogeneous taxonomic group is a group of similar species. Since Van Valen's work, various statistical approaches have been used to address the relationship between taxon age and the rate of extinction. We propose a general class of test statistics that can be used to test for the effect of age on the rate of extinction. These test statistics allow for a varying background rate of extinction and attempt to remove the effects of other covariates when assessing the effect of age on extinction. No model is assumed for the covariate effects. Instead we control for covariate effects by pairing or grouping together similar species. Simulations are used to compare the power of the statistics. We apply the test statistics to data on Foram extinctions and find that age has a positive effect on the rate of extinction. A derivation of the null distribution of one of the test statistics is provided in the supplementary material.     

Personality traits and strategic behavior: Anxiousness and aggressiveness in entry games

We demonstrate that personality has a systematic effect on strategic behavior. We focus on two personality traits: anxiousness and aggressiveness, and consider a 2-player entry game, where each player can guarantee a payoff by staying out, a higher payoff if she is the only player to enter, but a lower payoff if both players enter. We find that: anxious players enter less; aggressive players enter more; players are more likely to enter against anxious than non-anxious players; and players are less likely to enter against aggressive than non-aggressive players. We discuss the possible mechanism through which personality affects strategic behavior.     

Defender–Attacker Decision Tree Analysis to Combat Terrorism

We propose a methodology, called defender–attacker decision tree analysis, to evaluate defensive actions against terrorist attacks in a dynamic and hostile environment. Like most game‐theoretic formulations of this problem, we assume that the defenders act rationally by maximizing their expected utility or minimizing their expected costs. However, we do not assume that attackers maximize their expected utilities. Instead, we encode the defender's limited knowledge about the attacker's motivations and capabilities as a conditional probability distribution over the attacker's decisions. We apply this methodology to the problem of defending against possible terrorist attacks on commercial airplanes, using one of three weapons: infrared‐guided MANPADS (man‐portable air defense systems), laser‐guided MANPADS, or visually targeted RPGs (rocket propelled grenades). We also evaluate three countermeasures against these weapons: DIRCMs (directional infrared countermeasures), perimeter control around the airport, and hardening airplanes. The model includes deterrence effects, the effectiveness of the countermeasures, and the substitution of weapons and targets once a specific countermeasure is selected. It also includes a second stage of defensive decisions after an attack occurs. Key findings are: (1) due to the high cost of the countermeasures, not implementing countermeasures is the preferred defensive alternative for a large range of parameters; (2) if the probability of an attack and the associated consequences are large, a combination of DIRCMs and ground perimeter control are preferred over any single countermeasure.     

协调：一种应对公共政策执行阻滞现象的理念——基于公共政策执行中中央与地方的博弈分析

现有研究所提出的消解公共政策执行阻滞现象的对策多为事后性对策，且偏于刚性方式。以博弈论为理论依据，通过建构传统策略下中央与地方的策略互动、“协调”作为中央策略下的策略互动、协调引入博弈最始端下的策略互动三个博弈模型，比较得出将协调引入公共政策的制定和执行中，将有助于公共政策执行阻滞现象的减少和消除，并在此基础上提出以协调为理念构建的对策。     

Signaling to Partially Informed Investors in the Newsvendor Model

We analyze a signaling game between the manager of a firm and an investor in the firm. The manager has private information about the firm's demand and cares about the short‐term stock price assigned by the investor. Previous research has shown that under continuous decision choices and the Intuitive Criterion refinement, the least‐cost separating equilibrium will result, in which a low‐quality firm chooses its optimal capacity and a high‐quality firm over‐invests in order to signal its quality to investors. We build on this research by showing the existence of pooling outcomes in which low‐quality firms over‐invest and high‐quality firms under‐invest so as to provide identical signals to investors. The pooling equilibrium is practically appealing because it yields a Pareto improvement compared to the least‐cost separating equilibrium. Distinguishing features of our analysis are that: (i) we allow the capacity decision to have either discrete or continuous support, and (ii) we allow beliefs to be refined based on either the Undefeated refinement or the Intuitive Criterion refinement. We find that the newsvendor model parameters impact the likelihood of a pooling outcome, and this impact changes in both sign and magnitude depending on which refinement is used.     

Competition and Coordination in a Two‐Channel Supply Chain

We study competition and coordination in a supply chain in which a single supplier both operates a direct channel and sells its product through multiple differentiated retailers. We study analytically the supply chain with symmetric retailers and find that the supplier prefers to have as many retailers as possible in the market, even if the retailers' equilibrium retail price is lower than that of the supplier, and even if the number of retailers and their cost or market advantage prevent sales through the direct channel. We find that the two‐channel supply chain may be subject to inefficiencies not present in the single‐channel supply chain. We show that several contracts known to coordinate a single‐channel supply chain do not coordinate the two‐channel supply chain; thus we propose a linear quantity discount contract and demonstrate its ability to perfectly coordinate the two‐channel supply chain with symmetric retailers. We provide some analytical results for the supply chain with asymmetric retailers and propose an efficient solution approach for finding the equilibrium. We find numerically that the supplier still benefits from having more retailers in the market and that linear quantity discount contracts can mitigate supply chain inefficiency, though they no longer achieve perfect coordination.     

不同权力结构下制造商双渠道供应链的博弈分析

在单个拥有线下传统批发及线上直销双渠道的制造商和单个零售商组成的供应链中,基于供应链成员博弈权力的差异,构建制造商占优或零售商占优的两类Stackelberg博弈及双方同等权力的Nash博弈模型,分析了三种博弈权力结构对供应链成员价格,需求和利润的影响。研究发现：当制造商线下传统批发渠道所占市场份额较小时,（1）渠道交叉价格弹性系数为0时和不为0时,三种博弈权力结构对制造商双渠道供应链均衡解的影响具有一定的鲁棒性;（2）三种博弈权力结构下,制造商线上直销渠道价格相同;两类Stackelberg博弈权力结构下,线下传统批发渠道价格相同且大于Nash博弈下的传统渠道价格;制造商批发价格随其博弈主导地位下降逐渐降低;（3）当渠道交叉价格弹性系数为0时,三种博弈权力结构对线上直销渠道需求的影响是无差异的;当渠道间交叉价格弹性系数不为0时,两类Stackelberg博弈权力结构下的线下传统批发渠道需求相同且小于Nash博弈下的传统渠道需求,线上直销渠道需求相同且大于Nash博弈下的线上直销渠道需求;（4）三种博弈策略下,制造商收益及零售商收益随其博弈主导地位下降逐渐降低;Nash博弈下,供应链总利润最大。     

共享单车用户机会主义行为的演化博弈分析

目前为止,共享单车用户的机会主义行为是共享单车能否发展的关键制约因素之一。基于此,尝试用演化博弈理论建立共享单车企业与用户间的演化博弈模型发掘用户的机会主义行为动因及利益相关者作用。研究表明:用户收益是其行为选择的决定性因素,用户机会主义行为收益大于规范行为收益是机会主义行为的产生根源;共享单车企业的激励约束可对用户行为起到调节作用,约束强度将对用户机会主义行为的程度产生负向影响。最后,针对演化博弈模型分析结果,提出了相应管理对策建议。     

售电侧改革、市场主体变化与电价红利:基于讨价还价博弈

本文通过构建“一对多”和“多对多”讨价还价博弈模型,研究了售电侧改革前后,发电商和售电公司之间关于消费者剩余分配的博弈过程。具体来说,文章从售电侧改革带来的博弈主体与博弈机制变化角度,揭示了售电侧改革对用户电价红利的影响。研究发现:售电侧放开后,电力市场交易机制由“一对多”竞价上网变为“多对多”讨价还价匹配,造成了售电侧博弈主体的议价能力下降,发电侧博弈主体相对议价能力上升。发电商群体将索取更多的消费者剩余,从而推动发电侧整体报价的上涨,挤压了售电侧的利润空间,导致售电公司被迫抬高市场电价,最终剥夺了用户的电价红利。研究揭示了售电侧改革未能带来电价下降的根本原因。