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On the Relationship between p-Dominance and Stochastic Stability in Network Games 论网络博弈中p优势与随机稳定性的关系
Pub Date : 2018-08-19 DOI: 10.2139/ssrn.3234959
Daniel C. Opolot
Evolutionary models with persistent randomness employ stochastic stability as a solution concept to identify more reasonable outcomes in games with multiple equilibria. The complexity of computational methods used to identify stochastically stable outcomes and their lack of robustness to the interaction structure limit the applicability of evolutionary selection theories. This paper identifies p-dominance and contagion threshold as the properties of strategies and interaction structure respectively that robustly determine stochastically stable outcomes. Specifically, we show that p-dominant strategies, which are best responses to any distribution that assigns them a weight of at least p, are stochastically stable in networks with contagion threshold of at least p.
具有持续随机性的进化模型使用随机稳定性作为解决方案概念,在具有多个均衡的博弈中确定更合理的结果。用于识别随机稳定结果的计算方法的复杂性以及它们对相互作用结构缺乏鲁棒性限制了进化选择理论的适用性。本文认为p优势和传染阈值分别是决定随机稳定结果的策略和相互作用结构的特性。具体地说,我们表明p优势策略,即对分配权重至少为p的任何分布的最佳反应,在传染阈值至少为p的网络中是随机稳定的。
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引用次数: 2
Multi-Product Newsvendor Problem with Customer-Driven Demand Substitution: A Stochastic Integer Program Perspective 顾客驱动需求替代下的多产品报贩问题:随机整数规划视角
Pub Date : 2018-05-31 DOI: 10.2139/ssrn.3188361
Jie Zhang, Weijun Xie, S. Sarin
This paper studies a multi-product newsvendor problem with customer-driven demand substitution, where each product, once run out of stock, can be proportionally substituted by the others. This problem has been widely studied in the literature, however, due to nonconvexity and intractability, only limited analytical properties have been reported and no efficient approaches have been proposed. This paper first completely characterizes the optimal order policy when the demand is known and reformulates this nonconvex problem as a binary quadratic program. When the demand is random, we formulate the problem as a two-stage stochastic integer program, derive several necessary optimality conditions, prove the submodularity of the profit function, and also develop polynomial-time approximation algorithms and show their performance guarantees. We further propose a tight upper bound via nonanticipativity dual, which is proven to be very close to the optimal value and can yield a good-quality feasible solution under a mild condition. Our numerical investigation demonstrates effectiveness of the proposed algorithms. Moreover, several useful findings and managerial insights are revealed from a series of sensitivity analyses.
本文研究了一个客户驱动的多产品报摊问题,其中每一种产品一旦缺货,可以按比例被其他产品替代。这一问题在文献中得到了广泛的研究,但由于其非凸性和难处理性,只报道了有限的解析性质,没有提出有效的方法。本文首先完整地刻画了需求已知时的最优订货策略,并将该非凸问题重新表述为二元二次规划。当需求是随机时,我们将问题表述为一个两阶段随机整数规划,推导出若干必要的最优性条件,证明了利润函数的子模块性,并提出了多项式时间逼近算法,并给出了它们的性能保证。我们进一步利用非预期对偶提出了一个紧上界,证明了该上界非常接近最优值,并且在温和条件下可以得到一个高质量的可行解。我们的数值研究证明了所提出算法的有效性。此外,从一系列的敏感性分析中揭示了一些有用的发现和管理见解。
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引用次数: 7
Dynamic Selling Mechanisms for Product Differentiation and Learning 产品差异化的动态销售机制与学习
Pub Date : 2018-05-20 DOI: 10.2139/ssrn.2530261
N. B. Keskin, J. Birge
We consider a firm that designs a menu of vertically differentiated products for a population of customers with heterogeneous quality sensitivities. The firm faces an uncertainty about production costs, and we formulate this uncertainty as a belief distribution on a set of cost models. Over a time horizon of T periods, the firm can dynamically adjust its menu and make noisy observations on the underlying cost model through customers’ purchasing decisions. We characterize how optimal product differentiation depends on the “informativeness” of quality choices, formally measured by a contrast-to-noise ratio defined on the firm’s feasible quality set. We prove that, if there exist informative quality choices, then the optimal product differentiation policy improves the product quality to accelerate information accumulation and exercises the most extreme experimentation on less quality-sensitive customers. We design a minimum quality standard (MQS) policy that mimics the aforementioned features of the optimal policy and show that the MQS policy is near-optimal. We also prove that, if there exists a certain continuum of informative quality choices, then even a myopic policy that makes no attempt to learn exhibits near-optimal profit performance. This stands in stark contrast to the poor performance of myopic policies in pricing and learning problems in the absence of product differentiation.
我们考虑一家公司,为具有不同质量敏感性的客户群体设计垂直差异化产品的菜单。企业面临着生产成本的不确定性,我们将这种不确定性表述为一组成本模型上的信念分布。在T期的时间范围内,公司可以动态调整其菜单,并通过客户的购买决策对潜在成本模型进行嘈杂的观察。我们描述了最优产品差异化如何依赖于质量选择的“信息量”,通过定义在公司可行质量集上的对比度-噪声比正式测量。我们证明,如果存在信息质量选择,那么最优产品差异化策略提高了产品质量,加速了信息积累,并在对质量不太敏感的客户上进行了最极端的实验。我们设计了一个最低质量标准(MQS)策略,它模仿了上述最优策略的特征,并表明MQS策略是接近最优的。我们还证明,如果存在信息质量选择的某种连续体,那么即使是不尝试学习的短视政策也会表现出接近最优的利润表现。这与缺乏产品差异化的定价和学习问题上的短视政策表现不佳形成鲜明对比。
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引用次数: 22
Creative Class Competition and Innovation in the Absence of patent Protection 无专利保护下的创意阶层竞争与创新
Pub Date : 2018-04-17 DOI: 10.2139/ssrn.3269958
A. Batabyal
Recently, Batabyal and Yoo (2018) have analyzed Schumpeterian competition in a region that is creative a la Richard Florida and where the creative class is made up of existing and candidate entrepreneurs. These researchers assume that an existing entrepreneur has a fully enforced patent on the inputs or machines that he has produced. We dispense with this assumption and study a scenario in which there is no patent protection for the representative existing entrepreneur (REE). This REE can undertake two possible types of innovation at the same cost. The first (second) type of innovation is general (specific) and hence can (cannot) be copied by the so called candidate entrepreneurs. In this setting, we perform two tasks. First, we show that although the REE will never undertake the general innovation, he may undertake the specific innovation. Second, we point out that even though the general innovation is not undertaken, the value to the creative region from the general innovation exceeds that from the specific innovation.
最近,Batabyal和Yoo(2018)分析了一个地区的熊彼特竞争,该地区像理查德佛罗里达州一样富有创造力,创意阶层由现有和候选企业家组成。这些研究人员假设,一个现有的企业家对他所生产的投入或机器拥有完全强制执行的专利。我们抛弃了这一假设,并研究了一个对代表性现有企业家(REE)没有专利保护的场景。这个REE可以以相同的成本进行两种可能的创新。第一(第二)种创新是一般的(特定的),因此可以(不可以)被所谓的候选企业家复制。在此设置中,我们执行两个任务。首先,我们证明了REE虽然永远不会进行一般创新,但他可以进行特定创新。其次,我们指出,即使不进行一般创新,一般创新对创意区域的价值也超过了具体创新的价值。
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引用次数: 0
Dynamic Procurement of New Products with Covariate Information: The Residual Tree Method 协变量信息下新产品动态采购:残差树方法
Pub Date : 2018-03-28 DOI: 10.2139/ssrn.2926028
Gah-Yi Ban, Jérémie Gallien, A. Mersereau
Problem definition: We study the practice-motivated problem of dynamically procuring a new, short-life-cycle product under demand uncertainty. The firm does not know the demand for the new product ...
问题定义:研究需求不确定条件下动态采购短生命周期新产品的实践驱动问题。该公司不知道新产品的需求。
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引用次数: 62
Dynamic Inventory Control with Stockout Substitution and Demand Learning 基于缺货替代和需求学习的动态库存控制
Pub Date : 2018-03-23 DOI: 10.2139/ssrn.3157345
Boxiao Chen, X. Chao
We consider an inventory control problem with multiple products and stockout substitution. The firm knows neither the primary demand distribution for each product nor the customers’ substitution probabilities between products a priori, and it needs to learn such information from sales data on the fly. One challenge in this problem is that the firm cannot distinguish between primary demand and substitution (overflow) demand from the sales data of any product, and lost sales are not observable. To circumvent these difficulties, we construct learning stages with each stage consisting of a cyclic exploration scheme and a benchmark exploration interval. The benchmark interval allows us to isolate the primary demand information from the sales data, and then this information is used against the sales data from the cyclic exploration intervals to estimate substitution probabilities. Because raising the inventory level helps obtain primary demand information but hinders substitution demand information, inventory decisions have to be carefully balanced to learn them together. We show that our learning algorithm admits a worst-case regret rate that (almost) matches the theoretical lower bound, and numerical experiments demonstrate that the algorithm performs very well. This paper was accepted by J. George Shanthikumar, big data analytics.
考虑一个具有多产品和缺货替代的库存控制问题。公司既不知道每种产品的主要需求分布,也不知道顾客在产品之间的先验替代概率,它需要从动态的销售数据中学习这些信息。这个问题的一个挑战是,企业无法从任何产品的销售数据中区分主要需求和替代(溢出)需求,并且无法观察到损失的销售。为了克服这些困难,我们构建了学习阶段,每个阶段由一个循环勘探方案和一个基准勘探间隔组成。基准区间允许我们将主要需求信息从销售数据中分离出来,然后将该信息与来自循环勘探区间的销售数据相比较,以估计替代概率。由于提高库存水平有助于获得主要需求信息,但阻碍了替代需求信息,因此库存决策必须仔细平衡以同时了解它们。我们表明,我们的学习算法承认最坏情况的后悔率(几乎)匹配理论下界,数值实验表明,该算法执行得很好。本文被大数据分析J. George Shanthikumar接受。
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引用次数: 20
Economizing the Uneconomic: Markets for Reliable, Sustainable, and Price Efficient Electricity 节约不经济:可靠、可持续和价格高效的电力市场
Pub Date : 2018-03-13 DOI: 10.2139/ssrn.3140080
M. Rasouli, D. Teneketzis
Current electricity markets do not efficiently achieve policy targets i.e., sustainability, reliability, and price efficiency. Thus, there are debates on how to achieve these targets by using either market mechanisms e.g., carbon and capacity markets, or non-market mechanisms such as offer-caps, price-caps, and market-monitoring. At the same time, major industry changes including demand response management technologies and large scale batteries bring more elasticity to demand; such changes will impact the methodology needed to achieve the above mentioned targets. This work provides market solutions that capture all three policy targets simultaneously and take into account the above-mentioned industry changes. The proposed solutions are based on: (i) a model of electricity markets that captures all the above mentioned electricity policy targets; (ii) mechanism design and the development of a framework for design of efficient auctions with constraints (individual, joint homogeneous, and joint non-homogeneous). The results show that, within the context of the proposed model, all policy targets can be achieved efficiently by separate capacity and carbon markets in addition to efficient spot markets. The results also highlight that all three policy targets can be achieved without any offer-cap, price-cap, or market monitoring. Thus, within the context of the proposed model, they provide clear answers to the above-mentioned policy debates.
目前的电力市场并没有有效地实现政策目标,即可持续性、可靠性和价格效率。因此,关于如何通过使用市场机制(如碳和能力市场)或非市场机制(如供价上限、价格上限和市场监测)来实现这些目标存在争论。与此同时,包括需求响应管理技术和大规模电池在内的重大行业变革为需求带来了更大的弹性;这些变化将影响实现上述目标所需的方法。这项工作提供了同时捕捉所有三个政策目标并考虑到上述行业变化的市场解决方案。建议的解决方案基于:(i)电力市场模型,该模型涵盖了上述所有电力政策目标;(ii)机制设计和框架开发,以设计具有约束的有效拍卖(单个、联合均质和联合非均质)。结果表明,在该模型的背景下,除了有效的现货市场外,单独的产能和碳市场可以有效地实现所有政策目标。研究结果还强调,这三个政策目标都可以在没有要约上限、价格上限或市场监督的情况下实现。因此,在拟议模式的范围内,它们为上述政策辩论提供了明确的答案。
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引用次数: 0
Constant Job-Allowance Policies for Appointment Scheduling: Performance Bounds and Numerical Analysis 预约调度的恒定工作津贴政策:性能界限和数值分析
Pub Date : 2018-03-02 DOI: 10.2139/ssrn.3133508
Shenghai Zhou, Yichuan Ding, W. T. Huh, Guohua Wan
We consider the appointment scheduling problem, which determines the job allowance over the planning horizon. In particular, we study a simple but effective scheduling policy -- the so-called plateau policy, which allocates a constant job allowance for each appointment. Prior studies on appointment scheduling suggests a "dome" shape structure for the optimal job allowance over the planning horizon. This implies that job allowance does not vary significantly in the middle of the schedule sequence, but varies at the beginning and also at the end of the optimal schedule. Using a dynamic programming formulation, we derive an explicit performance gap between the plateau policy and the optimal schedule, and examine how this gap behaves as the number of appointments increases. We show that a plateau policy is asymptotically optimal when the number of appointments increases. We extend this result to a more general setting with multiple service types. Numerical experiments show that the plateau policy is near optimal even for a small number of appointments, which complements the theoretical results that we derived. Our result provides a justification and strong support for the plateau policy, which is commonly used in practice. Moreover, with minor modifications, the plateau policy can be adapted to more general scenarios with patient no-shows or heterogeneous appointment types.
我们考虑预约调度问题,该问题决定了计划范围内的工作津贴。我们特别研究了一种简单而有效的调度策略——所谓的平台策略,它为每次约会分配恒定的工作津贴。先前关于预约安排的研究表明,在规划范围内,最优工作津贴采用“圆顶”形状结构。这意味着工作津贴在计划序列的中间变化不大,但在最优计划的开始和结束时变化很大。使用动态规划公式,我们推导了平台策略和最优调度之间的显式性能差距,并研究了该差距随着预约数量的增加而如何表现。我们证明,当预约数量增加时,平台策略是渐近最优的。我们将此结果扩展到具有多个服务类型的更一般的设置。数值实验表明,即使在少量的约会中,平台策略也接近最优,这补充了我们推导的理论结果。研究结果为实践中普遍采用的高原政策提供了依据和有力支持。此外,只要稍加修改,平台政策就可以适应更普遍的情况,如患者未到诊或异质预约类型。
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引用次数: 2
Low-Acuity Patients Delay High-Acuity Patients in an Emergency Department 急诊科的低视力患者延误了高视力患者
Pub Date : 2017-12-31 DOI: 10.2139/ssrn.3095039
M. Bayati, Sara Kwasnick, Danqi Luo, E. Plambeck
This paper provides evidence that in an emergency department (ED), the arrival of an additional low-acuity patient substantially increases the wait time to start of treatment for high-acuity patients. This contradicts a long-standing prior conclusion in the medical literature that this effect is "negligible". The prior methodology underestimates the effect by neglecting how delays are propagated in queueing systems. In contrast, this paper develops and validates a new estimation method based on queueing theory, machine learning, and causal inference. Wait time information displayed to low-acuity patients provide a quasi-randomized instrumental variable, and is used to correct for omitted variable bias. Through a combination of empirical and queueing theoretic analyses, this paper identifies the two primary mechanisms by which a low-acuity patient increases the wait time for high-acuity patients: pre-triage delay and transition-delay. Thus the paper identifies ways to reduce high-acuity patients' wait time, including: reducing the standard deviation or mean of the transition delay in preemption, preventing transition delays by providing vertical or "fast track" treatment to more low-acuity patients; and designing wait time information systems to divert (especially when the ED is highly congested) low-acuity patients that do not need ED treatment.
本文提供的证据表明,在急诊科(ED),一个额外的低视力患者的到来大大增加了等待时间,以开始治疗的高视力患者。这与长期以来医学文献中认为这种影响“可以忽略不计”的结论相矛盾。先前的方法由于忽略了延迟在排队系统中的传播方式而低估了影响。相比之下,本文开发并验证了一种基于排队理论、机器学习和因果推理的新估计方法。显示给低视力患者的等待时间信息提供了一个准随机的工具变量,并用于纠正遗漏的变量偏差。通过实证分析和排队理论分析相结合,本文确定了低度急症患者增加高度急症患者等待时间的两个主要机制:分诊前延迟和转诊延迟。因此,本文确定了减少高度度患者等待时间的方法,包括:减少抢占转移延迟的标准差或平均值,通过向更多的低度度患者提供垂直或“快速通道”治疗来防止转移延迟;设计等待时间信息系统,以分流(特别是在急诊科高度拥挤时)不需要急诊科治疗的低视力患者。
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引用次数: 9
Leveraging Comparables for New Product Sales Forecasting 利用可比性进行新产品销售预测
Pub Date : 2017-12-11 DOI: 10.2139/ssrn.3086237
Lennart Baardman, Igor Levin, G. Perakis, Divya Singhvi
Many firms regularly introduce new products. Before the launch of any new product, firms need to make various operational decisions, which are guided by the sales forecast. The new product sales forecasting problem is challenging when compared to forecasting sales of existing products. For existing products, historical sales data gives an indicator of future sales, but this data is not available for a new product. We propose a novel sales forecasting model that is estimated with data of comparable products introduced in the past. We formulate the problem of clustering products and fitting forecasting models to these clusters simultaneously. Inherently, the model has a large number of parameters, which can lead to an overly complex model. Hence, we add regularization to the model so that it can estimate sparse models. This problem is computationally hard, and as a result, we develop a scalable algorithm that produces a forecasting model with good analytical guarantees on the prediction error. In close collaboration with our industry partner Johnson & Johnson Consumer Companies Inc., a major fast moving consumer goods manufacturer, we test our approach on real datasets, after which we check the robustness of our results with data from a large fast fashion retailer. We show that, compared to several widely used forecasting methods, our approach improves MAPE and WMAPE by 20-60% across various product segments compared to several widely used forecasting methods. Additionally, for the consumer goods manufacturer, we develop a fast and easy-to-use Excel tool that aids managers with forecasting and making decisions before a new product launch.
许多公司定期推出新产品。在推出任何新产品之前,公司都需要在销售预测的指导下做出各种经营决策。与现有产品的销售预测相比,新产品的销售预测问题具有挑战性。对于现有产品,历史销售数据提供了未来销售的指标,但对于新产品,此数据不可用。我们提出了一种新的销售预测模型,该模型是用过去引入的可比产品的数据来估计的。我们提出了聚类产品的问题,并同时对这些聚类拟合预测模型。从本质上讲,模型具有大量参数,这可能导致模型过于复杂。因此,我们在模型中加入正则化,使其能够估计稀疏模型。这个问题的计算难度很大,因此,我们开发了一种可扩展的算法,该算法产生的预测模型对预测误差有很好的分析保证。我们与我们的行业合作伙伴强生消费品公司(一家主要的快速消费品制造商)密切合作,在真实数据集上测试了我们的方法,之后我们用一家大型快速时尚零售商的数据检查了我们结果的稳健性。研究表明,与几种广泛使用的预测方法相比,我们的方法在各种产品细分领域的MAPE和WMAPE提高了20-60%。此外,我们为消费品制造商开发了一个快速易用的Excel工具,帮助经理在新产品发布之前进行预测和决策。
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引用次数: 34
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Operations Research eJournal
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