Tractable Consideration Set Structures for Assortment Optimization and Network Revenue Management

Discrete‐choice models are widely used to model consumer purchase behavior in assortment optimization and revenue management. In many applications, each customer segment is associated with a consideration set that represents the set of products that customers in this segment consider for purchase. The firm has to make a decision on what assortment to offer at each point in time without the ability to identify the customer's segment. A linear program called the Choice‐based Deterministic Linear Program (CDLP) has been proposed to determine these offer sets. Unfortunately, its size grows exponentially in the number of products and it is NP‐hard to solve when the consideration sets of the segments overlap. The Segment‐based Deterministic Concave Program with some additional consistency equalities (SDCP+) is an approximation of CDLP that provides an upper bound on CDLP's optimal objective value. SDCP+ can be solved in a fraction of the time required to solve CDLP and often achieves the same optimal objective value. This raises the question under what conditions can one guarantee equivalence of CDLP and SDCP+. In this study, we obtain a structural result to this end, namely that if the segment consideration sets overlap with a certain tree structure or if they are fully nested, CDLP can be equivalently replaced with SDCP+. We give a number of examples from the literature where this tree structure arises naturally in modeling customer behavior.     

金融资产收益跳跃行为的微观机制

文章发展了一个均衡模型,从微观机理角度解释了为什么资产价格会发生不频繁的跳跃行为.在该模型中,投资者学习不可直接观测的、真实的经济系统状态并为此支付成本的行为诱发了资产价格的跳跃行为.而投资者是否选择学习的行为则取决于投资者的偏好参数和收入的条件波动率.     

Quantitative convergence assessment for Markov chain Monte Carlo via cusums

Yu (1995) provides a novel convergence diagnostic for Markov chain Monte Carlo (MCMC) which provides a qualitative measure of mixing for Markov chains via a cusum path plot for univariate parameters of interest. The method is based upon the output of a single replication of an MCMC sampler and is therefore widely applicable and simple to use. One criticism of the method is that it is subjective in its interpretation, since it is based upon a graphical comparison of two cusum path plots. In this paper, we develop a quantitative measure of smoothness which we can associate with any given cusum path, and show how we can use this measure to obtain a quantitative measure of mixing. In particular, we derive the large sample distribution of this smoothness measure, so that objective inference is possible. In addition, we show how this quantitative measure may also be used to provide an estimate of the burn-in length for any given sampler. We discuss the utility of this quantitative approach, and highlight a problem which may occur if the chain is able to remain in any one state for some period of time. We provide a more general implementation of the method to overcome the problem in such cases.     

论我国呆帐准备金制度的未来选择

贷款呆帐准备金制度是国际上商业银行普遍采用的弥补贷款损失的制度。改革我国现有呆帐准备金制度 ,是我国当前金融制度改革中的一个重要内容     

论庄周与萨特的存在哲学

庄周与萨特，对人的存在意识与存在方式都曾进行了痛苦而深刻的思考：关于个体孤独、绝对自由、悲观而乐观等命题，都曾是二者为命途多舛的人类生命所作的无奈而悲凉的存在选择，让我们看到东西方哲学家在人类认识世界、把握人生过程中观念思维超越时空的交互与相通。     

The Quality Adjusted Price Index in the Pure Characteristics Demand Model

This paper computes a quality adjusted price index for the personal computer CPU from 1996 to 2000. The index is based on the pure characteristics demand model. I first compute the quality adjusted price index for the whole market, and show that it is very comparable with the hedonic price index but more sensitive to changes in product quality. Two types of the hedonic index are considered. One is the dummy variable index and the other is the formulation in Pakes (2003). When I group consumers by their willingness to pay for attribute improvement, the index shows consumer groups are differently affected by their product choices.     

Parental choice and the rural primary school: Lifestyle,locality and loyalty

This paper discusses the geography of parental choice in a rural locale and shows how a group of parents negotiated their way through the process of primary school choice. Using ethnographic data collected through interviews and observations with parents and staff from three rural primary schools in England, the research utilises Bourdieu's concepts of capital, habitus and field to show how the resources and values the parents held affected the school choices they made. The paper demonstrates that the longer-term resident local parents were influenced not only by their cultural capital but also by familial ties and an emotional commitment to the rural locale and these parents were therefore more inclined to support their local school. In contrast, the more recent newcomer parents used their cultural capital and spatial power to shop around to find what they believed to be the ‘right’ school. The paper argues that the newcomer parents had less allegiance to place and hence to the symbolic position that the school holds within the rural community within which they lived.     

西部地区新型工业化道路的模式选择

通过对工业化模式的一般分析,结合西部地区要实现新型工业化的特殊性,提出了要根据西部地区的工业基础、资源禀赋、发展环境等方面条件,采取高新技术带动模式、点轴辐射模式、外部资本加西部资源模式、农业工业化模式,实现西部新型工业化的跨越式发展。     

BAYESIAN HIDDEN MARKOV MODELS FOR LONGITUDINAL COUNTS

This paper describes a Bayesian approach to modelling carcinogenity in animal studies where the data consist of counts of the number of tumours present over time. It compares two autoregressive hidden Markov models. One of them models the transitions between three latent states: an inactive transient state, a multiplying state for increasing counts and a reducing state for decreasing counts. The second model introduces a fourth tied state to describe non‐zero observations that are neither increasing nor decreasing. Both these models can model the length of stay upon entry of a state. A discrete constant hazards waiting time distribution is used to model the time to onset of tumour growth. Our models describe between‐animal‐variability by a single hierarchy of random effects and the within‐animal variation by first‐order serial dependence. They can be extended to higher‐order serial dependence and multi‐level hierarchies. Analysis of data from animal experiments comparing the influence of two genes leads to conclusions that differ from those of Dunson (2000). The observed data likelihood defines an information criterion to assess the predictive properties of the three‐ and four‐state models. The deviance information criterion is appropriately defined for discrete parameters.     

公共政策制定过程：利益综合与路径选择——全国妇联在《婚姻法》修改中的影响力

作为人民团体，全国妇联凭借着在中国现有政治结构中的特殊地位，履行着代表和维护妇女权益的职能。它通过多种路径选择积极参与《婚姻法》修改过程，施加了影响力，较好地展示了社会团体所应发挥的重要作用，体现出政策制定过程中的民主特性。