MARKET PENETRATION AND LOCATIONAL CONFLICT IN FRANCHISE SYSTEMS*

This paper addresses the questions of market penetration and locational conflict in a franchise system of distribution. The models developed provide a means to evaluate alternative scenarios and the effects of various franchise policies. It is shown that the market penetration and location goals of the members of a franchise system coincide only under a very limited set of circumstances.     

Influence diagnostics for the structural sharpe model under normal/independent distributions

A method is proposed in this paper to assess the local influence of minor perturbations for the Sharpe model when the normal distribution is replaced by normal/independent (NI) distributions. The family of NI distributions is an attractive class of symmetric heavy-tailed densities that includes as special cases the normal, t-Student, slash, and the contaminated normal distributions. Since the returns of the market are not observable, the statistical analysis is carried out in the context of an errors-in-variables model. An influence analysis for detecting influential observations (atypical returns) is developed to investigate the sensitivity of the maximum likelihood estimators. Diagnostic measures are obtained based on the conditional expectation of the complete-data log-likelihood function. The results are illustrated by using a set of shares of companies traded in the Chilean stock market.     

Correction to: The Impact of Agricultural Technologies on Poverty and Vulnerability of Smallholders in Ethiopia: A Panel Data Analysis

Social Indicators Research - The article The Impact of Agricultural Technologies on Poverty and Vulnerability of Smallholders in Ethiopia: A Panel Data Analysis, written by Wubneshe Dessalegn Biru,...     

Birthdate and mortality: an evaluation of the death-dip/death-rise

The effect on mortality of socially significant events is examined using birth date as the criterion date for a large sample from official state mortality records for Ohio. The sample consisted of all deaths from natural causes for 1979-1981. "The findings show that there is a greater tendency for persons to die within thirty days after the date of birth than before. More specifically, there was a statistically significant pattern of increased mortality for those who were never married and for ill-defined causes of death. A theoretical foundation and a brief interpretation of these findings is offered."     

Hypotheses testing for structural calibration model

The main objective of this paper is to discuss maximum likelihood inference for the comparative structural calibration model (Barnett, in Biometrics 25:129–142, 1969), which is frequently used in the problem of assessing the relative calibrations and relative accuracies of a set of p instruments, each designed to measure the same characteristic on a common group of n experimental units. We consider asymptotic tests to answer the outlined questions. The methodology is applied to a real data set and a small simulation study is presented.     

On diagnostics in multivariate measurement error models under asymmetric heavy-tailed distributions

In this paper, we discuss the extension of some diagnostic procedures to multivariate measurement error models with scale mixtures of skew-normal distributions (Lachos et?al., Statistics 44:541?C556, 2010c). This class provides a useful generalization of normal (and skew-normal) measurement error models since the random term distributions cover symmetric, asymmetric and heavy-tailed distributions, such as skew-t, skew-slash and skew-contaminated normal, among others. Inspired by the EM algorithm proposed by Lachos et?al. (Statistics 44:541?C556, 2010c), we develop a local influence analysis for measurement error models, following Zhu and Lee??s (J R Stat Soc B 63:111?C126, 2001) approach. This is because the observed data log-likelihood function associated with the proposed model is somewhat complex and Cook??s well-known approach can be very difficult to apply to achieve local influence measures. Some useful perturbation schemes are also discussed. In addition, a score test for assessing the homogeneity of the skewness parameter vector is presented. Finally, the methodology is exemplified through a real data set, illustrating the usefulness of the proposed methodology.     

Instruments for research on transition: Applied methods and approaches for exploring the transition of young care leavers to adulthood

Young people who have been in care show relatively poor outcomes in comparison to young people who have not been in care, and run a high risk of social exclusion. Therefore, the transition to adulthood of young people leaving care is an important topic for research. However, there is still little knowledge about the different research approaches and research instruments that are being used in studying this topic. The aim of the present study is to review the approaches and instruments that are used in empirical studies that focus on young care leavers' transitions to adulthood. The results show that the studies apply a diversity of topics and instruments, but that there is also considerable overlap. To make better comparisons on the transition from out-of-home care to adulthood between different countries, a common research framework and one or more research instruments should be developed that can assess this transition and the situation of young care leavers in diverse social contexts.     

Influence diagnostics for Grubbs’s model with asymmetric heavy-tailed distributions

Grubbs’s model (Grubbs, Encycl Stat Sci 3:42–549, 1983) is used for comparing several measuring devices, and it is common to assume that the random terms have a normal (or symmetric) distribution. In this paper, we discuss the extension of this model to the class of scale mixtures of skew-normal distributions. Our results provide a useful generalization of the symmetric Grubbs’s model (Osorio et al., Comput Stat Data Anal, 53:1249–1263, 2009) and the asymmetric skew-normal model (Montenegro et al., Stat Pap 51:701–715, 2010). We discuss the EM algorithm for parameter estimation and the local influence method (Cook, J Royal Stat Soc Ser B, 48:133–169, 1986) for assessing the robustness of these parameter estimates under some usual perturbation schemes. The results and methods developed in this paper are illustrated with a numerical example.