Bayesian covariance matrix estimation using a mixture of decomposable graphical models

We present a Bayesian approach to estimating a covariance matrix by using a prior that is a mixture over all decomposable graphs, with the probability of each graph size specified by the user and graphs of equal size assigned equal probability. Most previous approaches assume that all graphs are equally probable. We show empirically that the prior that assigns equal probability over graph sizes outperforms the prior that assigns equal probability over all graphs in more efficiently estimating the covariance matrix. The prior requires knowing the number of decomposable graphs for each graph size and we give a simulation method for estimating these counts. We also present a Markov chain Monte Carlo method for estimating the posterior distribution of the covariance matrix that is much more efficient than current methods. Both the prior and the simulation method to evaluate the prior apply generally to any decomposable graphical model.     

Children placed in out-of-home care: risk factors for involvement with the juvenile justice system

In previous research, child maltreatment has been associated with several negative outcomes, including delinquency. This study uses administrative data to examine risk factors, including the severity and chronicity of maltreatment, for juvenile justice involvement among children, ages 7 to 17, who were placed in out-of-home care in Florida (N = 13,212). The results of multivariate Cox regression analysis indicated that among specific types of maltreatment, sexual abuse was associated with the risk of faster placement only in a detention center. Additionally, findings from this study suggest that maltreatment chronicity but not maltreatment severity increases the chances of earlier involvement with the juvenile justice system among children who were placed in an out-of-home care. Implications of these findings are discussed.     

Training for frontline workers

This article examines the training needs of people who work directly with children and families–frontline workers. It argues that such people are working with child abuse, whether they have recognized this to be the case or not. The article outlines work that needs to be covered in training of frontline workers, in order that they can respond effectively to abused children and undertake appropriate prevention work. A range of relevant publications which can support this training are discussed.     

Global Civil Society and the Question of Global Citizenship

For many recent commentators, the association of citizenship with the nation-state is under siege, as transnational and even global forms of citizenship begin to emerge. The nascent phenomenon of global citizenship in particular is characterized by three components: the global discourse on human rights; a global account of citizenly responsibilities; and finally “global civil society.” This last component is supposed to give a new global citizenship its “political” character, and for many represents the most likely vehicle for the emergence of a global, democratic citizen politics. This paper critically examines this view, asking whether a global form of citizenship is indeed emerging, and if so whether “global civil society” is well-equipped to stand in as its political dimension. The paper examines two opposed narratives on the potential of global civil society to form a political arm of global citizenship, before returning by way of conclusion to the vexed notion of global citizenship itself.This paper draws from the final chapter of Rethinking Equality: the Challenge of Equal Citizenship, Manchester University Press, Manchester, 2006.     

Financial Strain and Depression Among Farm Operators: The Role of Perceived Economic Hardship and Personal Control1

Abstract The causal processes accounting for the relationship between farm financial strain and depression are not well understood. Using data from a statewide survey of North Carolina farm operators, we develop a covariance structure model that specifies relationships among farm financial strain, perceived economic hardship in the household, personal control, and depression. Analyses reveal that the relationship between farm financial strain and depression is mediated by perceptions of economic hardship and personal control. Results point to the importance of differential resilience to objective economic problems instead of differential exposure to these problems.     

Capital budgeting and lagrangian relaxation: A case study

This paper presents a new approach to the classical multiyear capital budgeting problem. Three basic operational principles, arising out of an actual implementation of such a model, are specifically addressed in this approach. These principles are: (1) all budgets except that of the first year possess a degree of flexibility; (2) the user favours a series of near optimal solutions to a single optimal solution; and (3) an effective low cost procedure for dealing with large problems is required. Using the particular example of capital budgeting in the area of highway maintenance, an algorithm is developed and computational results for a variety of problem sizes are presented.     

Talking Up the Game: Football and the Reconstruction of Liberia,West Africa

Most people will accept the contention that sport has an ideological site. Indeed sport might be considered as the broadest cultural denomination in many nations, capable of creating and sustaining a sense of identity and belonging crucial to national integration. Expressions around sport and, in this instance, specifically Association Football (soccer) appeal to individuals supportive of a variety of ideological perspectives. Thus, the pursuit of any understanding of the game has to be sought with reference to culturally specific power relations. The role that football can play in both the construction of national identity and the rehabilitation of the former militia in a war-damaged society is the focus of this ethnographic inquiry. The location is Liberia, West Africa, beginning in 1998, a year after the election that marked the end of almost a decade of civil conflict.     

Defence and attack: empire,nation and resistance in inter-war football in Malta

A nation's politics and socio-cultural identity can sometimes be best considered through the lens of Association Football (soccer). Examining football in the Mediterranean island of Malta in the inter-war years of 1920–1940 this paper focuses its analysis on the phenomenon that is the game of football and the epi-phenomena it provokes and sustains. In the tiny archipelago that constitutes the Maltese islands, the game as it was played and administered in this era had implications for the British colonialists, the refugees that fled Central Europe for Maltese shores and the indigenous Maltese peoples. In these years the game was played out amidst, variously, the island's unique party politics, intra-district rivalries, and historical considerations of reputation and social class. It was also to become integral to the contestations around anti-colonial sentiment and the debates over national identity. The game in Malta was thus a facilitator of both local and global processes and played an understated role in the pursuit of independence. This examination of the specific Maltese context may well shed light upon broader processes within the international game which lies at the intersection of the global and the local.     

Obtaining least absolute value estimates for a two-way classification model

The importance of the two-way classification model is well known, but the standard method of analysis is least squares. Often, the data of the model calls for a more robust estimation technique. This paper demonstrates the equivalence between the problem of obtaining least absolute value estimates for the two-way classification model and a capacitated transportation problem. A special purpose primal algorithm is developed to provide the least absolute value estimates. A computational comparison is made between an implementation of this specialized algorithm and a standard capacitated transportation code.