Book Reviews

The diagnostic tools examined in this article are applicable to regressions estimated with panel data or cross-sectional data drawn from a population with grouped structure. The diagnostic tools considered include (a) tests for the existence of group effects under both fixed and random effects models, (b) checks for outlying groups, and (c) specification tests for comparing the fixed and random effects models. A group-specific counterpart to the studentized residual is introduced. The methods are illustrated using a hedonic housing price regression.     

On proximity between PCA in the frequency domain and usual PCA

The principal components analysis (PCA) in the frequency domain of a stationary p-dimensional time series (X _n ) _n∈? leads to a summarizing time series written as a linear combination series X′ _n =∑ _m C _m ° X _n?m . Therefore, we observe that, when the coefficients C _m , m≠0, are close to 0, this PCA is close to the usual PCA, that is the PCA in the temporal domain. When the coefficients tend to 0, the corresponding limit is said to satisfy a property noted 𝒫, of which we will study the consequences. Finally, we will examine, for any series, the proximity between the two PCAs.     

Optimization problems for consecutive-2-out-of-n:G system

Abstract

This paper considers the optimization problems for a consecutive-2-out-of-n:G system where n is considered to be fixed or random. When the number of components is constant, the optimal number of components and the optimal replacement time are discussed by minimizing the expected cost rates. Furthermore, we focus on the above discussions again when n is a random variable. We give an approximate value of MTTF and propose the preventive replacement policy, respectively.     

A novel approach for evaluating programs designed to serve military veterans: Using an adapted common components analysis

Evaluators are challenged to keep pace with the vast array of Veteran support programs operating in the United States, resulting in a situation in which many programs lack any evidence of impact. Due to this lack of evidence, there is no efficient way to suggest which programs are most effective in helping Veterans in need of support. One potential solution to this dilemma is to reconceptualize program evaluation, by moving away from evaluating programs individually to evaluating what is common across programs. The Common Components Analysis (CCA) is one such technique that aggregates findings from programs that have undergone rigorous evaluation at the level of program components (e.g., content, process, barrier reduction). Given that many Veteran programs lack outcome evidence from rigorous studies, an adaptation to CCA is needed. This report examines cross-sectional data from a pilot study using an adapted CCA across five domains of well-being (i.e., employment, education, legal/financial/housing, mental/physical health, and social/personal relationships). The purpose of this preliminary study is to determine the feasibility of eliciting program nominations and program components from Veterans via an online survey. When coupled with a longitudinal research design, this adaptation to CCA will allow for stronger causal claims about the expected impact of different program components within and across a variety of domains.     

Demand and Production Management with Uniform Guaranteed Lead Time

Recently, innovation‐oriented firms have been competing along dimensions other than price, lead time being one such dimension. Increasingly, customers are favoring lead time guarantees as a means to hedge supply chain risks. For a make‐to‐order environment, we explicitly model the impact of a lead time guarantee on customer demands and production planning. We study how a firm can integrate demand and production decisions to optimize expected profits by quoting a uniform guaranteed maximum lead time to all customers. Our analysis highlights the increasing importance of lead time for customers, as well as the tradeoffs in achieving a proper balance between revenue and cost drivers associated with lead‐time guarantees. We show that the optimal lead time has a closed‐form solution with a newsvendor‐like structure. We prove comparative statics results for the change in optimal lead time with changes in capacity and cost parameters and illustrate the insights using numerical experimentation.     

A PANIC Attack on Unit Roots and Cointegration

This paper develops a new methodology that makes use of the factor structure of large dimensional panels to understand the nature of nonstationarity in the data. We refer to it as PANIC—Panel Analysis of Nonstationarity in Idiosyncratic and Common components. PANIC can detect whether the nonstationarity in a series is pervasive, or variable‐specific, or both. It can determine the number of independent stochastic trends driving the common factors. PANIC also permits valid pooling of individual statistics and thus panel tests can be constructed. A distinctive feature of PANIC is that it tests the unobserved components of the data instead of the observed series. The key to PANIC is consistent estimation of the space spanned by the unobserved common factors and the idiosyncratic errors without knowing a priori whether these are stationary or integrated processes. We provide a rigorous theory for estimation and inference and show that the tests have good finite sample properties.     

Determining the Number of Factors in Approximate Factor Models

In this paper we develop some econometric theory for factor models of large dimensions. The focus is the determination of the number of factors (r), which is an unresolved issue in the rapidly growing literature on multifactor models. We first establish the convergence rate for the factor estimates that will allow for consistent estimation of r. We then propose some panel criteria and show that the number of factors can be consistently estimated using the criteria. The theory is developed under the framework of large cross‐sections (N) and large time dimensions (T). No restriction is imposed on the relation between N and T. Simulations show that the proposed criteria have good finite sample properties in many configurations of the panel data encountered in practice.     

企业口碑营销管理的优化

口碑营销作为营销传播的一种有力方式,在新技术的支持下,其日益增强的影响力正在被人们重新认识。口碑营销依靠非正式组织进行传播,具有可信度高、针对性强、容易形成顾客忠诚等特点。为此,企业应通过确立传播主体,利用品牌进行推荐,引导顾客进行体验消费,并做好负面口碑管理来实现口碑营销管理的优化,使其最大限度地发挥威力。     

语力概念与意义表征

语力的概念可溯源至弗雷格,而对语力论的系统研究则发端于奥斯汀言语行为论的创立.语力概念的创立,填补了语言哲学中的一项空白,但围绕语力与意义的关系问题,塞尔等言语行为论的继承者并未因袭奥斯汀的观点.不过,与其把语力与意义这两个概念对立起来,毋宁将语力视为交际语用意义的组成部分,并作为意义的重要维度加以研究,从而通过对其性质及构成要素等的分析探察,进一步丰富语言哲学对于意义概念的理论表征.