A multivariate Poisson mixture model for marketing applications

This paper describes a multivariate Poisson mixture model for clustering supermarket shoppers based on their purchase frequency in a set of product categories. The multivariate nature of the model accounts for cross-selling effects between the purchases made in different product categories. However, for computational reasons, most multivariate approaches limit the covariance structure by including just one common interaction term, or by not including any covariance at all. Although this reduces the number of parameters significantly, it is often too simplistic as typically multiple interactions exist on different levels. This paper proposes a theoretically more complete variance/covariance structure of the multivariate Poisson model, based on domain knowledge or preliminary statistical analysis of significant purchase interaction effects in the data. Consequently, the model does not contain more parameters than necessary, whilst still accounting for the existing covariance in the data. Practically, retail category managers can use the model to devise customized merchandising strategies.     

Clusters,knowledge spillovers and new venture performance: An empirical examination

Firms in geographic regions with industry clustering have been hypothesized to possess performance advantages due to superior access to knowledge spillovers. Yet, no prior studies have directly examined the relationship between a firm's location within a cluster, knowledge spillovers and firm performance. In this study, we examine whether technological spillovers explain the performance of new ventures in cluster regions. We find that ventures located within geographic clusters absorb more knowledge from the local environment and have higher growth and innovation performance, but contrary to conventional wisdom, technological spillovers are not the contributing cause of higher performance observed for these firms.     

Pirates and invaders: Land acquisition in urban Colombia and Venezuela

In Bogotá the poor purchase the land on which they build their homes; in Valencia they invade public and private land. Why are there such different attitudes on the part of the state in the two cities? Why indeed do the local authorities discourage land invasion in Bogotá but permit illegal subdivisions, while in Valencia invasion settlements aresometimes positively encouraged and usually serviced? Does the difference lie in the local political situations, in the nature of the land market, in the planning or legislative framework or in the attitudes of the poor? Whatever the exact cause one fact remains clear; both mechanisms provide the poor with sufficient land to maintain political stability and to prevent incursions into the housing areas of the rich. Such outcomes are encouraged by the policies of the local service and planning agencies. So successful are these mechanisms indeed, that rather than providing a threat to the political and economic system, invasions and pirate urbanizations actively support it.     

Transfer payments and the Phillips Curve

Policy makers are today confronted with a worsening relationship between inflation and unemployment. Voluminous economic literature on the “Phillips Curve” has long attempted to show why inflation and unemployment are normally inversely correlated. More recent literature has sought to identify factors that could worsen the apparent tradeoff. This paper uses the labor sector of the System Dynamics National Model to analyze the potential impacts of increased transfer payments on inflation and unemployment. The results suggest that in the short run, higher transfer payments can prolong job search, thereby boosting unemployment, while simultaneously driving up wages due to reduced labor availability. But over the longer term, rising wages raise the attrractiveness of working, thereby compensating for higher transfer payments. Therefore, higher transfer payments are not permanently inflationary. Key long-run impacts of transfer payments may be to raise relative costs of labor, thereby lowering employment through factor substitution, and to discourage dropout from the labor force so as to maintain eligibility for payments.     

A geometric approach to disequilibrium exchange rate fluctuations: The case of Switzerland

This article deals with the effects of exchange rate fluctuations in non-Walrasian macromodels. A demand driven model (‘Keynesian Unemployment’) and a supply driven model (‘Classical Unemployment’), both estimated on Swiss data, are alternatively considered. In each case an exchange rate modification and possible accompanying policy measures are considered. The feasible consequences on employment and the balance of trade are investigated by means of a geometric comparative static technique. For each type of fix-price equilibrium, the favourable conditions for a devaluation and a revaluation are thus emphasised.     

Psychographic constructs and demographic segments

As marketers attempt to place advertisements based on demographic profiles, the use of psychographic information becomes more important. The purpose of this research is to evaluate the validity of selected psychographic measures as well as to then relate these constructs to demographic segments. The analysis, using LISREL VI, assesses the constructs, which then, based on MANOV, are related to demographic segments. Implications of the study for validating psychographic measures and for applying this knowledge are discussed. © 1995 John Wiley & Sons, Inc.     

Tests of functional form in dynamic econometric models: Some empirical experience

Econometric theory has provided several rival tests of functional form specifications in economic relations, but there is little empirical experience in using many of them. This note reports some practical applications, and compares the performance of various tests, in specifying dynamic econometric models.     

支持企业社会责任部门做该做的事

随着企业社会责任概念的兴起,许多企业已经建立了相关部门以便能够协助公司推动社会责任相关工作融入到日常运营当中。该一趋势固然是应该鼓励的,但是同时也必须观察和评估企业社会责任部门（以下简称＂CSR部门＂）的成效。有时候虽然CSR部门付出了巨大的努力,但是效果还是有限。问题在哪里呢？     

“里约+20”峰会的成效

为了促进国际间合作以应对环保、贫困等问题,改变全球经济发展模式,1992年,联合国在里约热内卢首次举办了针对可持续发展的高峰会议。会议中,政府界发表了《里约声明》并签署了《生物多样性公约》和《联合国气候变化框架公约》等国际公约。今年,     

Probabilistic access forecasting for improved offshore operations

Improving access is a priority in the offshore wind sector, driven by the opportunity to increase revenues, reduce costs, and improve safety at operational wind farms. This paper describes a novel method for producing probabilistic forecasts of safety-critical access conditions during crew transfers. Methods of generating density forecasts of significant wave height and peak wave period are developed and evaluated. It is found that boosted semi-parametric models outperform those estimated via maximum likelihood, as well as a non-parametric approach. Scenario forecasts of sea-state variables are generated and used as inputs to a data-driven vessel motion model, based on telemetry recorded during 700 crew transfers. This enables the production of probabilistic access forecasts of vessel motion during crew transfer up to 5 days ahead. The above methodology is implemented on a case study at a wind farm off the east coast of the UK.