A Graphical Diagnostic for Identifying Influential Model Choices in Bayesian Hierarchical Models

Abstract. Real‐world phenomena are frequently modelled by Bayesian hierarchical models. The building‐blocks in such models are the distribution of each variable conditional on parent and/or neighbour variables in the graph. The specifications of centre and spread of these conditional distributions may be well motivated, whereas the tail specifications are often left to convenience. However, the posterior distribution of a parameter may depend strongly on such arbitrary tail specifications. This is not easily detected in complex models. In this article, we propose a graphical diagnostic, the Local critique plot, which detects such influential statistical modelling choices at the node level. It identifies the properties of the information coming from the parents and neighbours (the local prior) and from the children and co‐parents (the lifted likelihood) that are influential on the posterior distribution, and examines local conflict between these distinct information sources. The Local critique plot can be derived for all parameters in a chain graph model.     

The Additive Risk Model for Estimation of Effect of Haplotype Match in BMT Studies

Abstract. In this article we consider a problem from bone marrow transplant (BMT) studies where there is interest on assessing the effect of haplotype match for donor and patient on the overall survival. The BMT study we consider is based on donors and patients that are genotype matched, and this therefore leads to a missing data problem. We show how Aalen's additive risk model can be applied in this setting with the benefit that the time‐varying haplomatch effect can be easily studied. This problem has not been considered before, and the standard approach where one would use the expected‐maximization (EM) algorithm cannot be applied for this model because the likelihood is hard to evaluate without additional assumptions. We suggest an approach based on multivariate estimating equations that are solved using a recursive structure. This approach leads to an estimator where the large sample properties can be developed using product‐integration theory. Small sample properties are investigated using simulations in a setting that mimics the motivating haplomatch problem.     

A FRAMEWORK FOR THE SYSTEM DESIGN PROCESS1

Much discussion and writing about “systems” is often superficial, glib, and of a non-operational nature. This paper presents a cohesive framework for the process of system design which is felt to be of operational value in the design and management of systems. The framework's central tenet is that all systems are made up of entities and the relationships among the attributes of those entities; and that in designing systems, two processes are used, inclusion and structuring. Inclusion is concerned with what entities to include in a system and structuring with how their attributes are to be related. The system design process is directed or driven by a set (system) of criteria. Systems must be viewed with a time dimension: evolution will and should take place, both in the systems themselves and, more importantly, in the criteria that drive the design and evolution of those systems. In this framework, all problem solvers can usefully regard themselves as system designers. Presentation of the framework is followed by examples, discussion of the criteria set, system design tools, and some implications for teachers and practitioners.     

Rethinking the origins of transnational humanitarian organizations: the curious case of the International Shipwreck Society

This exploration of the evolution of the International Shipwreck Society (ISS) – a previously neglected transnational humanitarian organization that by the late 1830s had branches in every continent – casts new light on three key aspects of the development of global humanitarianism. First, that there was a secular humanitarian association with a global organizational structure in the 1830s challenges widespread assumptions about the timing of internationally organized humanitarian action. Second, the influence of Chinese precedents on the ISS points to the importance of long forgotten Eastern origins of transnational humanitarianism. And third, the evaluation of the role of individuals in the development of the ISS reveals that early transnational humanitarian organizations faced leadership problems that scholars had previously neglected. In each of these respects, this article provides a new perspective on the origins of global networks.     

FLEXIBLE CONTRACTS AND SUBJECTIVE WELL‐BEING

Theory suggests that when workers choose between permanent and flexible contracts, their utility should tend to equalize across contract types. New estimates of job satisfaction show the critical role played by unmeasured worker heterogeneity. They reveal that flexible contracts are a strong negative determinant of satisfaction with job security but are often a positive determinant of other dimensions of job satisfaction. As a consequence, flexible contracts have either a weak negative influence or no influence on overall job satisfaction. Moreover, flexible contracts generally have no impact on overall life satisfaction of the employed. These results appear broadly consistent with the presence of equalizing differences. (JEL J28, J41)