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.     

The journey effect: how travel affects the experiences of mental health in-patient service-users and their families

The qualitative study presented in this paper explored the perspectives of service-users, family members and staff about the impact of travel issues on the lives of mental health in-patients and carers. This topic was chosen because it was prioritised by members of Xplore, a service-user and carer research group, and has received little research attention. Travel problems were a significant issue for many service-users and carers, bound-up with mental health issues and the recovery experience. Travel facilitation through the funding of taxis and the provision of guides was appreciated. A few service-users and carers positively valued distancing from their previous home environment. The meaning of travel issues could only be understood in the context of individuals’ wider lives and relationships. The significance of the findings is discussed in relation to the social model of disability.     

Social Work Students as Market Consumers: Faculty Perceptions of Customer Service Expectations

Social work education has become a consumers market, and social work faculty are increasingly expected to fill certain customer service roles in order to retain students as customers. Using the Academic Entitlement Questionnaire, this study sought to examine social work faculty in the USA (N = 57) who are members of the Association of Baccalaureate Social Work Program Directors listserv perceptions of student customer service expectations. Findings were that these social work faculty are under increased pressure to fill certain customer service roles, and that they feel conflict about doing so. Implications for the delivery of social work education and practice are explored.     

读中国文学还是读中国——兼论对外汉语教学中的跨文化主题阅读法

对外汉语教学中的外国留学生（outsider／‘局外人’）与中国学生（insider／‘局内人’）是两个不同的读者群体。然而，两个不同读者群体的文学课程却存在很大的相似性。这些相似性体现出对外汉语文学课程受到中文作为母语教育传统和实践的深刘影响。局内人课程传统和实践影响到对外汉语教学作为第二语言教学的特点在课程设置和教学层面上的实现。同时，也有违对外汉语教学‘学生中心’的原则。本文在此基础上，尝试性地提出针对留学生特点和需要的文化阅读的概念一以提高跨文化交际能力为目的的跨文化主题阅读法。其目的在于探讨通过创新性的阅读方法更有效地进行文化传播和文化教学。     

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.     

Estimation across multiple models with application to Bayesian computing and software development

Statistical models are sometimes incorporated into computer software for making predictions about future observations. When the computer model consists of a single statistical model this corresponds to estimation of a function of the model parameters. This paper is concerned with the case that the computer model implements multiple, individually-estimated statistical sub-models. This case frequently arises, for example, in models for medical decision making that derive parameter information from multiple clinical studies. We develop a method for calculating the posterior mean of a function of the parameter vectors of multiple statistical models that is easy to implement in computer software, has high asymptotic accuracy, and has a computational cost linear in the total number of model parameters. The formula is then used to derive a general result about posterior estimation across multiple models. The utility of the results is illustrated by application to clinical software that estimates the risk of fatal coronary disease in people with diabetes.     

Populism and the Rise of the Reform Party in Alberta*

L'augmentation rapide du soutien populaire accordé au Reform Party of Canada est abordée du point de vue de deux théories déjà anciennes de mobilisation populiste-la première axée sur la position de classe et la seconde privilégiant le nativisme. Les données issues d'une enquête effectuêe dans toute la province en 1991 révèlent que les agriculteurs, un segment particulier de la petite bourgeoisie, ont tendance plus que tout autre groupe à accorder leur vote au Reform Party au cours d'une élection fédérate. Les Albertains qui se décrivent comme «Canadiens» plutôt qu'appartenant à un groupe ethnique ou racial particulier et, à un degré moindre, les répondants d'origine anglo-saxonne ou celtique, semblent un peu plus enclins à soutenir le Reform Party. De plus, les Albertains qui ont de fortes convictions sur certains dossiers sociaux et politiques (multicultu-ralisme, égalité des sexes, statut distinct du Québec, indulgence envers les criminels) sont également attirés par le Reform Party, ainsi que les personnes qui se sentent généralement aliénées sur le plan politique. The early rise in popular support for the Reform Party of Canada is discussed from the vantage point of two long-standing theories of populist mobilization, the first focussing on class position and the second emphasizing nativism. Data from a province-wide survey of Alberta residents conducted in 1991 reveal that farmers, a particular segment of the petite bourgeoisie, were more likely than any other class group to state that they would vote Reform in a federal election. Albertans who identified themselves as Canadians rather than identifying with a particular ethnic or racial group, and to a lesser extent those of Anglo-Saxon/Celtic origin, were somewhat more likely to support the Reform Party. In addition, Albertans with strong feelings on a number of specific social and political issues (multiculturalism, gender equality, distinct status for Quebec, lenient treatment of criminals) were also attracted to the Reform Party, as were those who felt generally politically alienated.     

Union decertification election outcomes: Bargaining unit characteristics and union resources

Previous analysis using aggregate data has concluded that union decertification activity is “exclusively a product of market conditions.” We employ data disaggregated by local (county) labor market which permits a preliminary investigation of the importance of potential nonmarket influences that are not measurable using aggregate data, namely, the type of bargaining unit, the type of union, the type of employer, and proxies for union resources. It also allows a more precise specification of the labor market characteristics previously found to influence decertification. Our results confirm the importance of market conditions in decertification activity and outcomes, but they also suggest that the likelihood of decertification is much greater in independent unions and in industry-county combinations in which the typical employee works part-time and has limited alternative income opportunities. Institutional characteristics of the union and employer, individual characteristics of bargaining unit members, and local economic conditions are important determinants of decertification.