Sub-Saharan Africa in depression: The impact on the welfare of children

This paper analyses the impact of the economic crisis on the welfare of children in Sub-Saharan Africa, an area which includes most of the least developed and most severely affected countries. These countries are characterized by: low levels of skilled personpower, dependency on their primary product exports, small industrial sectors, a lagging food production growth, a high proportion of rural population and a child dependency ratio that is virtually 1 to 1. The situations of Nigeria, Zambia and Tanzania are examined in detail. In Zambia where there is substantial evidence of worsening of the condition of children in the 1970s, the most urgent requirement is additional resources, particularly foreign exchange. Such is also the case with Tanzania, while Nigeria does have the resources to develop a more coherent economy and finance basic services adequately.     

Staying Power of Churn Prediction Models

In this paper, we study the staying power of various churn prediction models. Staying power is defined as the predictive performance of a model in a number of periods after the estimation period. We examine two methods, logit models and classification trees, both with and without applying a bagging procedure. Bagging consists of averaging the results of multiple models that have each been estimated on a bootstrap sample from the original sample. We test the models using customer data of two firms from different industries, namely the internet service provider and insurance markets. The results show that the classification tree in combination with a bagging procedure outperforms the other three methods. It is shown that the ability to identify high risk customers of this model is similar for the in-period and one-period-ahead forecasts. However, for all methods the staying power is rather low, as the predictive performance deteriorates considerably within a few periods after the estimation period. This is due to the fact that both the parameter estimates change over time and the fact that the variables that are significant differ between periods. Our findings indicate that churn models should be adapted regularly. We provide a framework for database analysts to reconsider their methods used for churn modeling and to assess for how long they can use an estimated model.     

Dynamic stochastic copula models: estimation,inference and applications

We propose a new dynamic copula model in which the parameter characterizing dependence follows an autoregressive process. As this model class includes the Gaussian copula with stochastic correlation process, it can be viewed as a generalization of multivariate stochastic volatility models. Despite the complexity of the model, the decoupling of marginals and dependence parameters facilitates estimation. We propose estimation in two steps, where first the parameters of the marginal distributions are estimated, and then those of the copula. Parameters of the latent processes (volatilities and dependence) are estimated using efficient importance sampling. We discuss goodness‐of‐fit tests and ways to forecast the dependence parameter. For two bivariate stock index series, we show that the proposed model outperforms standard competing models. Copyright © 2010 John Wiley & Sons, Ltd.     

Über verschärfungen der Tschebycheff'schen ungleichung

Abstract

In der vorliegenden Arbeit werden im Anschluss an Arbeiten von K. Pearson [8]¹, A. Guldberg [5], Birger Meidell, [2], C. Lurquin [7], A. Camp [3], P. O. Berge [1]. M. Fréchet [4] u. a. weitere Versohärfungen des Tschebycheffschen Theorems behandelt und am Beispiel der Normalverteilung in ein und mehreren Variabeln durchgeführt.     

Cervical injuries in Sweden,a national survey of patient data from 1987 to 1999

Neck injuries are one of the most important injuries as they have the potential to influence the spinal cord. Data from most parts of the world are not sufficient to define a comprehensive view of mortality, morbidity, disability and handicap due to neck injuries. In Sweden, there are no data on the incidence of neck injuries. The aim of this study is to define the national incidence and causes of neck injuries in Sweden. An incidence study was undertaken with data from the injury surveillance program at the Swedish National Board of Health and Welfare. The investigation includes cervical vertebral fractures reported between 1987 and 1999, and cervical soft tissue injuries over a period of three years, from 1997 to 1999. Data between 1987 and 1996 were reported in ICD 9, while data from 1997 to 1999 were reported in ICD 10. During the study period, 14,310 non-fatal and 782 fatal cervical injuries occurred. A decreasing incidence for cervical fractures can be seen for the Swedish population, except for the elderly that have a slight increase in incidence. The incidence for cervical soft tissue injuries is almost constant. Cervical fractures demand longer periods of hospitalization than the soft tissue injuries. Transportation-related cervical fractures have dropped since 1991, while soft tissue injuries increased slowly between 1997 and 1999. Fall accidents are now the largest external cause of cervical fractures, and the population above 65 years accounts for almost 50% of the fall accidents. The male population has a higher incidence of cervical fractures, disregarding age. It is concluded that safety programs for transportation-related injuries in Sweden have been successful, while fall accidents are still substantial. Much more can be done to prevent neck injuries; especially to reduce the number of transportation-related cervical soft tissue injuries and fall injuries in the elderly population.     

Radical innovation in a small firm: a hybrid electric vehicle development project at Volvo Cars

The potential paradigmatic shift in technology from the internal combustion engine to electric propulsion via hybrid electric vehicles (HEVs) has been addressed by most automakers, and has produced very different outcomes. This paper uses the framework of core capabilities to discuss how the small automaker, Volvo Cars, made substantial progress in its HEV development using an approach based on limited resources and a low risk. A comparison with Toyota's successful but very resource‐demanding Prius project reveals some factors contributing towards rapid development in a context of limited resources, including focused project objectives, tight collaboration with suppliers of the new technologies, reuse of existing technologies and an unaggressive, bottom‐up approach to change the firm's values and norms and other core capability dimensions. This paper provides an empirical illustration of how a small company in a mature industry worked with radical innovation in a development project drawing on the combination of organizational slack, entrepreneurial employees and an extensive use of external (knowledge) suppliers.     

The changing dynamics of regionalism in South Korea's elections

One of the most persistent areas of discussion regarding South Korea's party and election systems is the continued elevation of regional personalities over political institutions. We seek to pour new wine into old bottles, however, by challenging a seldom‐considered assumption in Korean studies; that regionalism has exerted constant pressures across regime, province, and personality. There is a void in studying how transition to democracy has affected the dominance of personality‐based regionalism in Korean politics. We investigate democratization's impact on this phenomenon by examining the provincial distribution of legislative and presidential voting from 1971–2002. We employ a new indicator for personality‐based disproportionality, apply it to election outcomes at the provincial level, and find that the electoral impact of regionalism has changed over time across regimes, provinces, and political personalities. We find that regional voting disproportionality 1) increased immediately after transition; 2) has varied depending on personality and type of election; 3) is indeed low in provinces traditionally labeled as neutral; and 4) increased in the 2000 legislative election while declining in the 2002 presidential election.