MANAGING VENDOR INVENTORY IN A DUAL LEVEL DISTRIBUTION SYSTEM

Collaborative arrangements among members of the supply chain have received a great deal of interest in recent years as a means of reducing costs. One such arrangement is vendor managed inventory (VMI). VMI allows the vendor to make decisions concerning the quantity and timing of deliveries to the retailer. Such an arrangement offers the potential of a more efficient supply chain by removing the negative effects of retail ordering policies. A thorough review of the literature was conducted to identify factors likely to impact the performance of a VMI partnership. Computer simulation was used to study the effects of these factors from both the vendor's and retailer's perspectives. The results lend insight into the performance of VMI and guidance for managers as to the environments in which VMI is most effective.     

A dynamic approach to the analysis of strategic alliances

The increasing trend in strategic alliance formation between major firms around the world, has prompted researchers from various disciplines to look at this phenomenon in great detail. In this paper, we review alternate approaches in the literature in this area. We then propose a non-linear dynamic approach to study the formation of competitive strategic alliances and contrast it with the traditional game-theoretic approach. The pros and cons of these two approaches are discussed with reference to a competitive alliance scenario. Dynamic models have significant managerial implications as they enable us to investigate ‘if-then’ type scenarios and project the impact of different strategies.     

Progressive stress accelerated life tests under finite mixture models

In this paper, progressive stress accelerated life tests are considered when the lifetime of a product under use condition follows a finite mixture of distributions. The experiment is performed when each of the components in the mixture follows a general class of distributions which includes, among others, the Weibull, compound Weibull, power function, Gompertz and compound Gompertz distributions. It is assumed that the scale parameter of each component satisfies the inverse power low, the progressive stress is directly proportional to time and the cumulative exposure model for the effect of changing stress holds. Based on type-I censoring, the maximum likelihood estimates (MLEs) of the parameters under consideration are obtained. A special attention is paid to a mixture of two Rayleigh components. Simulation results are carried out to study the precision of the MLEs and to obtain confidence intervals for the parameters involved.     

CEV模型的单位根检验研究

CEV模型（Constant Elasticity of Variance Model）作为常用的利率模型，在实证分析中得到了广泛运用，但是其单位根检验一直被忽略或者被默认可以使用迪基一富勒检验。本文首次运用Box—Cox变换的技巧，针对CEV模型的单位根检验问题，找到了合适的统计量并且证明其渐进分布存在，然后通过蒙特卡罗方法求出了该统计量的分布表。得到了在大样本的情形下可以沿用迪基一富勒检验，但在小样本的情形下与迪基一富勒检验有所偏差的结论。     

SELECTION BIAS CORRECTIONS BASED ON THE MULTINOMIAL LOGIT MODEL: MONTE CARLO COMPARISONS

Abstract.  This survey presents the set of methods available in the literature on selection bias correction, when selection is specified as a multinomial logit model. It contrasts the underlying assumptions made by the different methods and shows results from a set of Monte Carlo experiments. We find that, in many cases, the approach initiated by Dubin and MacFadden (1984) as well as the semi-parametric alternative recently proposed by Dahl (2002) are to be preferred to the most commonly used Lee (1983) method. We also find that a restriction imposed in the original Dubin and MacFadden paper can be waived to achieve more robust estimators. Monte Carlo experiments also show that selection bias correction based on the multinomial logit model can provide fairly good correction for the outcome equation, even when the IIA hypothesis is violated.     

A Bayesian approach for more reliable tail risk forecasts

This paper demonstrates that existing quantile regression models used for jointly forecasting Value-at-Risk (VaR) and expected shortfall (ES) are sensitive to initial conditions. Given the importance of these measures in financial systems, this sensitivity is a critical issue. A new Bayesian quantile regression approach is proposed for estimating joint VaR and ES models. By treating the initial values as unknown parameters, sensitivity issues can be dealt with. Furthermore, new additive-type models are developed for the ES component that are more robust to initial conditions. A novel approach using the open-faced sandwich (OFS) method is proposed which improves uncertainty quantification in risk forecasts. Simulation and empirical results highlight the improvements in risk forecasts ensuing from the proposed methods.     

The Bank of England quarterly model of the UK economy

The Bank of England first acquired a macroeconomic model of the UK economy in early 1973, and used it for forecasting in June and July of that year. The initial model was obtained from the London Business School (LBS), but the last 14 years or so have, on the part of both the Bank and the LBS, led to developments which now make the models no closer to each other than to other large scale models of the UK. This article describes the structure and central properties of the current version of the Bank model, which has some 663 variables, 134 of which are modelled by behavioural equations, 153 by technical equations, 212 identities and 164 exogenous variables. In order to provide a transitional step between the kind of models with which most macroeconomists are familiar and the full scale version of the Bank model, one part of the article presents a very simple stylized version of the full model. This is a stepping stone to the full model which is described and analysed on a sectoral basis in Part 3, with a complete listing of equations in Part 4. Some of the simulation properties, and hence full model dynamic responses, are considered in Part 5.     

Estimation methods for stochastic volatility models: a survey

Abstract.  Although stochastic volatility (SV) models have an intuitive appeal, their empirical application has been limited mainly due to difficulties involved in their estimation. The main problem is that the likelihood function is hard to evaluate. However, recently, several new estimation methods have been introduced and the literature on SV models has grown substantially. In this article, we review this literature. We describe the main estimators of the parameters and the underlying volatilities focusing on their advantages and limitations both from the theoretical and empirical point of view. We complete the survey with an application of the most important procedures to the S&P 500 stock price index.     

An analysis of the process generating de facto standards in the PC spreadsheet software market

This paper develops a model to analyze the emergence of de facto or market defined compatibility standards in the market for PC spreadsheet software over the period 1982–1988. The model is capable of integrating diverse fragments of empirical evidence and a number of important theoretical building blocks, in particular the analysis of gateways between different versions of the same package, product preannouncements, and diverse consumer tastes towards intrinsic quality and network externalities. The model also explores the implications of different functional forms for the relationship between installed base and the value of network externalities. The paper finds that at least some enhancements to the basic model of standards have to be incorporated to offer a reasonable approximation to developments in the PC spreadsheet software market. The simplest model of de facto standards is not able to describe developments in this market.     

Werbewirkung durch Imagery-Processing

Zusammenfassung Die Frage, warum bestimmte Informationen oder Werbemittel mehr und andere weniger Überzeugungskraft aufweisen, beschäftigt die Marketingforschung und verwandte Gebiete schon seit geraumer Zeit. Eine dieser Thematik zuzuordnende Forschungsrichtung, die in den letzten zwanzig Jahren eine Forschungstradition entwickelte, ist die Imagery-Forschung. Autoren, die sich dieser Forschungsrichtung zuwenden, erklären die Wirkung von Informationen damit, dass die Elemente in dieser Information Gedächtnisinhalte oder Imaginationen (Fantasien bzw. Vorstellungen) bei den Rezipienten auslösen, die ihrerseits die Bewertung des relevanten Meinungs- oder Werbeobjekts beeinflussen. In diesem Beitrag wird zunächst dargestellt, welche Hypothesen im Mittelpunkt der neueren Imagery-Forschung stehen. Der Nutzen dieser Überlegungen besteht zum Beispiel für die Werbepraxis darin, dass konkrete Hinweise für die Werbegestaltung gegeben werden. Anschließend wird der Stand der empirischen Forschung zu diesen Hypothesen vorgestellt. Hier zeigt sich, dass die empirischen Erkenntnisse hinter dem Stand der theoretischen Forschung zurückgeblieben sind. Am Ende dieser Abhandlung werden Vorschläge unterbreitet, wie die theoretischen Überlegungen einer weitergehenden Analyse unterzogen werden können. JEL classifications M31, M37