A Semi-Parametric Quantile Function Estimator for Use in Bootstrap Estimation Procedures

In this note we develop a new quantile function estimator called the tail extrapolation quantile function estimator. The estimator behaves asymptotically exactly the same as the standard linear interpolation estimator. For finite samples there is small correction towards estimating the extreme quantiles. We illustrate that by employing this new estimator we can greatly improve the coverage probabilities of the standard bootstrap percentile confidence intervals. The method does not reqiure complicated calculations and hence it should appeal to the statistical practitioner.     

Issues in applying recent CPMP ‘Points to Consider’ and FDA guidance documents with biostatistical implications

The International Conference on Harmonisation guideline ‘Statistical Principles for Clinical Trials’ was adopted by the Committee for Proprietary Medicinal Products (CPMP) in March 1998, and consequently is operational in Europe. Since then more detailed guidance on selected topics has been issued by the CPMP in the form of ‘Points to Consider’ documents. The intent of these was to give guidance particularly to non‐statistical reviewers within regulatory authorities, although of course they also provide a good source of information for pharmaceutical industry statisticians. In addition, the Food and Drug Administration has recently issued a draft guideline on data monitoring committees. In November 2002 a one‐day discussion forum was held in London by Statisticians in the Pharmaceutical Industry (PSI). The aim of the meeting was to discuss how statisticians were responding to some of the issues covered in these new guidelines, and to document consensus views where they existed. The forum was attended by industry, academic and regulatory statisticians. This paper outlines the questions raised, resulting discussions and consensus views reached. It is clear from the guidelines and discussions at the workshop that the statistical analysis strategy must be planned during the design phase of a clinical trial and carefully documented. Once the study is complete the analysis strategy should be thoughtfully executed and the findings reported. Copyright © 2003 John Wiley & Sons, Ltd.     

Patterns in Cross Shopping for Groceries and their Implications for Co-operation in Retail Location

One determinant of the success of a retail outlet is its location. The location strategies adopted by many retailers of convenience products, including those marketing groceries, have been based upon the principle of siting stores away from competition. Recent moves by leading grocery retailers to develop out of town and other sites jointly, where they would trade side by side, mean that methods are needed to appraise the selection of location partners to supplement or replace traditional, spatial analyses. A method based on similarity of image and cross-shopping behaviour is proposed and tested on two substantial data bases. A concept, drawn from theory on brand switching, that customers would treat outlets seen as similar in a similar way, is found not to apply to source switching. Source switching behaviour is found instead to vary with the source itself, according to two distinct patterns. In one, shoppers cross shop more to retailers perceived to be similar; in the other, shoppers cross shop more to retailers perceived to be different. The strategies currently adopted by four grocery retailers in joint site development are appraised against the model of source switching that can be defined from these patterns. Some location alliances are predicted to be potentially more valuable to one partner than another both in the short and long term. The anomalies identified in the selection of location partners are analysed by reference to concepts drawn from the literature on co-operation. Two different types of relationship exist between the various retail partners; a longer term alliance at each site and shorter co-operation between head offices. It is suggested that the nature of the second could prejudice the outcome of the first.     

Modelling map positional error to infer true feature location

The authors consider the issue of map positional error, or the difference between location as represented in a spatial database (i.e., a map) and the corresponding unobservable true location. They propose a fully model‐based approach that incorporates aspects of the map registration process commonly performed by users of geographic informations systems, including rubber‐sheeting. They explain how estimates of positional error can be obtained, hence estimates of true location. They show that with multiple maps of varying accuracy along with ground truthing data, suitable model averaging offers a strategy for using all of the maps to learn about true location.     

The vegetarian option: varieties, conversions, motives and careers

This paper reports the findings of a qualitative study of the dietary beliefs and practices of a ‘snowball sample’ of seventy-six vegetarians and vegans. The dynamics of the process of conversion are examined, along with respondents'accounts of their motives and of the impact of their dietary stance upon their relationships with kin, friends and colleagues. The study's findings, which appear to indicate the central importance of ethical considerations for this particular response group, are set in the context of broader debates concerning the sociological dimensions of the selection or avoidance of specific food items.     

Strategic planning for the board

Although the planning operation is regarded by some observers as unrealistic in conditions of rapid change and increasing competition, the discipline of strategic thinking and the need for strategic leadership continue to be of vital importance. The author examines the purpose of the Board of Directors and its role in the management of strategy.     

Telling lies in everyday life: Motivational and organizational consequences of sequential preferences

This study of a collection of self-observed lies told in everyday interactions indicated that all informants lied; that lying was, generally, an easy and spontaneous activity; and that our varied informants told lies in much the same manner and for the same reasons. The analysis of the general features of the interactions in which lies were embedded showed that many lies are the consequence of a preference system that promotes acceptance and hides rejection in the sequential organization of interaction. The lies found in pre-acceptance and pre-rejection sequences indicate that both parties contrive for acceptance. The negative cases of lies told in rejection of deprecating assessments suggest a broader theoretical template that encompasses the lies told for acceptance as a subset of the interactional preference for social solidarity. In contrast to the view that telling lies undermines social cohesion by interfering with trust, this study indicates that many lies are told to affirm affiliation.