Optimising the queuing system for an ear, nose and throat outpatient clinic

Several authors have considered the problem of the efficient running of hospital outpatient clinics. The first solution was probably by Welch & Bailey (1952). More recent authors include Fetter & Thompson (1966), Vissers (1979), Stafford & Aggarwal (1979). The Ear, Nose and Throat outpatient clinic presents a special case due to the complex queuing structure involved, which is described in the next section. A simulation of this special clinic was undertaken, any useful theoretical results being impossible to obtain.     

Multidimensional scaling used in multivariate statistical process control

This paper considers the use of multidimensional scaling techniques in multivariate statistical process control. Principal components analysis, multiple principal components analysis, partial least squares and PARAFAC models have already been established as useful methods for such, but it should be possible to widen the portfolio of techniques to include others that come under the multidimensional scaling class. Some of these are briefly described-namely classical scaling, non-metric scaling, biplots, Procrustes analysis-and are then used on some gas transportation data provided by Transco.     

Estimating the number of clusters in a data set via the gap statistic

We propose a method (the 'gap statistic') for estimating the number of clusters (groups) in a set of data. The technique uses the output of any clustering algorithm (e.g. K -means or hierarchical), comparing the change in within-cluster dispersion with that expected under an appropriate reference null distribution. Some theory is developed for the proposal and a simulation study shows that the gap statistic usually outperforms other methods that have been proposed in the literature.     

Alternative forms of the wald test: how long is a piece of string?

It is possible to obtain any positive value for the Wald test statistic, by rewriting the null hypothesis being tested In an algebraically equivalent form.     

Functional linear discriminant analysis for irregularly sampled curves

We introduce a technique for extending the classical method of linear discriminant analysis (LDA) to data sets where the predictor variables are curves or functions. This procedure, which we call functional linear discriminant analysis ( FLDA ), is particularly useful when only fragments of the curves are observed. All the techniques associated with LDA can be extended for use with FLDA. In particular FLDA can be used to produce classifications on new (test) curves, give an estimate of the discriminant function between classes and provide a one- or two-dimensional pictorial representation of a set of curves. We also extend this procedure to provide generalizations of quadratic and regularized discriminant analysis.     

Technology and institutions: living in a material world

This article addresses the relationship between technology and institutions and asks whether technology itself is an institution. The argument is that social theorists need to attend better to materiality: the world of things and objects of which technical things form an important class. It criticizes the new institutionalism in sociology for its failure to sufficiently open up the black box of technology. Recent work in science and technology studies (S&TS) and in particular the sociology of technology is reviewed as another route into dealing with technology and materiality. The recent ideas in sociology of technology are exemplified with the author’s study of the development of the electronic music synthesizer.

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Roads to Poverty Reduction? Exploring Rural Roads' Impact on Mobility in Africa and Asia

Within current poverty reduction programmes, focus on the social‐welfare millennium development goals is widening to embrace a concern with infrastructural investment, particularly for remote areas. The previously popular assumption that rural disadvantage can be remedied by road‐building is resurfacing. Using survey data from Ethiopia, Zambia and Vietnam, this article explores how effective such investment is in addressing mobility and social‐service accessibility in rural areas. The findings indicate that, in extremely remote areas, road improvements may catalyse the expansion of social‐service provision, as evidenced in Ethiopia. However, given the poor's relative lack of motor vehicles and ability to pay for public transport, they are, by no means, a sufficient condition for enhancing the mobility of the rural poor.