AN INDEX FOR THE MEASUREMENT OF CONSUMER LOYALTY*

The concept of consumer “loyalty” (i.e., preference for a particular store or brand) is intriguing to marketing scholars and practitioners. Research in this area would be enhanced by the acceptance of an operational measure of consumer loyalty. Loyalty appears to be a tri-dimensional concept; per cent of budget, allocated to the store or brand, amount of switching, and number of alternatives explored have been used to measure loyalty. Consequently, the authors propose a “loyalty index” which combines these three measures. An empirical test of the proposed index showed that the index did discriminate among degrees of consumer loyalty, and was related to consumer psychological characteristics in a manner similar to that of the generally used single measures of consumer loyalty.     

USING DUMMY VARIABLES TO CHECK FOR ROUNDING ERROR IN COMPUTERIZED REGRESSION PROGRAMS*

After a brief review of the role of dummy variables in regression analysis and the current state-of-the art in rounding/truncation error detection in computerized least squares programs, this paper presents a theorem that can be used to detect this type of error whenever an analyst is running a regression program that has one (or more) dummy variables as independent variables.     

Transforming sub-Saharan Africa

This article provides an analysis of my personal experience and research on the need for sub-Saharan African economic transformation. It contains relevant references to econometric modeling which are consistent with this analysis. After presenting the causes of African failures, ranging from the alleged role of slavery and colonization, to trade composition and relative decline, to present day problems of governance, low level of foreign investment in Africa, and mass unemployment, the article concludes with an agenda for the transformation of sub-Saharan Africa.     

Feature significance in generalized additive models

This paper develops inference for the significance of features such as peaks and valleys observed in additive modeling through an extension of the SiZer-type methodology of Chaudhuri and Marron (1999) and Godtliebsen et al. (2002, 2004) to the case where the outcome is discrete. We consider the problem of determining the significance of features such as peaks or valleys in observed covariate effects both for the case of additive modeling where the main predictor of interest is univariate as well as the problem of studying the significance of features such as peaks, inclines, ridges and valleys when the main predictor of interest is geographical location. We work with low rank radial spline smoothers to allow to the handling of sparse designs and large sample sizes. Reducing the problem to a Generalised Linear Mixed Model (GLMM) framework enables derivation of simulation-based critical value approximations and guards against the problem of multiple inferences over a range of predictor values. Such a reduction also allows for easy adjustment for confounders including those which have an unknown or complex effect on the outcome. A simulation study indicates that our method has satisfactory power. Finally, we illustrate our methodology on several data sets.     

Minimum contrast estimation of random processes based on information of second and third orders

This paper presents the results on consistency and asymptotic normality of a class of minimum contrast estimators for random processes with short- or long-range dependence based on the second- and third-order cumulant spectra. Asymptotic properties of sample spectral functionals of second and third orders, which are of independent interest in view of their possible use for nonparametric estimation of processes with short- or long-range dependence, are also provided.     

Optimality and bias of some interpolation and extrapolation designs

We consider interpolation and extrapolation designs with controlled bias. A consistent estimate of an upper bound of the bias is presented. The estimate of some extrapolated value is obtained in a two-stage procedure. The first one provides an estimate of some interpolated value. The second one uses a Taylor expansion around this point. This procedure yields a new type of designs. We discuss their optimality properties with respect to the variance and the bias.     

A simulation study of a discrete-time multiserver retrial queue with finite population

In this paper, we deal with a discrete-time multiserver retrial queue with finite population. Firstly, we study the Markov chain at the epochs immediately after slot boundaries making emphasis on the computation of its steady-state distribution. Then, the main performance measures are investigated. Besides, we simulate the waiting time of a customer in the retrial group under three different queueing policies. Some numerical examples are given to illustrate the analysis.     

Bayesian design in queues: An application to aeronautic maintenance

We exploit Bayesian criteria for designing M/M/c//r$M/M/c//r$ queueing systems with spares. For illustration of our approach we use a real problem from aeronautic maintenance, where the numbers of repair crews and spare planes must be sufficiently large to meet the necessary operational capacity. Bayesian guarantees for this to happen can be given using predictive or posterior distributions.     

Retracted and replaced: Sodium cromoglicate: an ineffective drug or meta‐analysis misused?

The following article from Pharmaceutical Statistics, Sodium cromoglicate: an ineffective drug or meta‐analysis misused? by M. T. Stevens, A. M. Edwards, J. B. L. Howell published online on 15 March 2007 in Wiley InterScience ( www.interscience.wiley.com ), has been retracted by agreement between the author, the journal Editor in Chief, Steven Julious, and John Wiley & Sons, Ltd. The retraction has been agreed because the article is not yet ready for publication and an early version without revisions was published in error. Replacement article pending. Copyright © 2007 John Wiley & Sons, Ltd.     

The Zen of physician initiatives

Many physicians today feel ravaged by the brutal speed with which change has been occurring. They see the beliefs and practices of a lifetime being abandoned and replaced by the flavor of the month, management du jour. But if you are willing and able to take the brave step of approaching your physicians without an agenda, meeting with them to listen to their concerns, and can also avoid hanging a lightning-rod label on every bright new idea that comes out of the sessions, you'll be on the way to effective new management. This new style is a "Zen" approach (but don't give it that label) that lets real collaboration come into the place that is supposed to be all about healing--the health care organization. From "never call it anything" to "stay with them until they get it," ideas on how to be a Zen manager are presented, with the ultimate goal of truly partnering with physicians and infusing them with a desire to move beyond the frustration and disenchantment they are feeling.