Using the EM-algorithm for survival data with incomplete categorical covariates

Incomplete covariate data is a common occurrence in many studies in which the outcome is survival time. With generalized linear models, when the missing covariates are categorical, a useful technique for obtaining parameter estimates is the EM by the method of weights proposed in Ibrahim (1990). In this article, we extend the EM by the method of weights to survival outcomes whose distributions may not fall in the class of generalized linear models. This method requires the estimation of the parameters of the distribution of the covariates. We present a clinical trials example with five covariates, four of which have some missing values.     

THE FAMILY CRISIS INTERVENTION LITERATURE: WHAT IS MEANT BY “FAMILY”?*

Family crisis intervention is a rapidly growing area of clinical care in family therapy which lacks clear conceptualization, especially with respect to how “family” fits into crisis intervention theory. This paper integrates recent concepts from the family therapy literature into three views: family as background, family as context, and family as a unit. The family crisis intervention literature (56 publications) is reviewed and categorized according to these three views. Clarity in how “family” is viewed and consistency between theory and practice are examined. Recommendations for improving the conceptualization of “family” in family crisis intervention theory and practice are made.     

Looking Forward Not Looking Back: The Evaluation of Community Living

This article outlines the development of evaluative methods within the field of mental handicap services. It suggests that evaluators have too often taken for granted the tacit assumptions underlying service models, using these to determine the criteria for evaluating success. It argues that evaluators should be more explicit about the values they adopt, and what patterns of life services should be enabling people to achieve. By more closely linking evaluation criteria to what people with a mental handicap should achieve, evaluation can become more effective in promoting positive change in service models. The article describes an approach developed by the authors for the evaluation of the 'All-Wales Strategy for the Development of Services for Mentally Handicapped People'.     

An analysis of two probabilistic model induction techniques

Two probabilistic model induction techniques, cart and constructor, are compared, via a series of experiments, in terms of their ability to induce models that are both interpretable and predictive. The experiments show that, although both algorithms are able to deliver classifiers with predictive performance close to that of the optimal Bayes rule,constructor is able to generate a probabilistic model that is more easily interpretable than the cart model. On the other hand, cart is a more mature algorithm and is capable of handling many more situations (e.g., real-valued training sets) thanconstructor. A variety of characteristics of both algorithms are compared, and suggestions for future research are made.     

Participation in Practice

This paper is one of a series written by members of the Mental Handicap Research Project at the University College of North Wales in connection with the All-Wales Strategy. Previous papers describe local arrangements for the planning of new services and discuss in general terms issues concerning partnership and participation. This paper describes modes of parental participation in the planning of new services for the mentally handicapped.     

Online surveys for BGLT research: issues and techniques

Online surveys are becoming increasingly popular for accessing less visible and decentralized populations, including bisexual, gay, lesbian and transgender (BGLT) populations. Advances in technology and convenience for the both the researcher and the participant have facilitated this trend. In this paper, we explore issues related to conducting BGLT survey research online, such as making decisions about survey formats, target populations and recruitment, compensation, access.