Properties of doubly-truncated gamma variables

The truncated gamma distribution has been widely studied, primarily in life-testing and reliability settings. Most work has assumed an upper bound on the support of the random variable, i.e. the space of the distribution is (0,u). We consider a doubly-truncated gamma random variable restricted by both a lower (l) and upper (u) truncation point, both of which are considered known. We provide simple forms for the density, cumulative distribution function (CDF), moment generating function, cumulant generating function, characteristic function, and moments. We extend the results to describe the density, CDF, and moments of a doubly-truncated noncentral chi-square variable.     

Beyond bifurcation: Examining the conventions of organic agriculture in New Zealand

The last 10 years have witnessed numerous attempts to evaluate the merits of new theoretical approaches – ranging from Actor Network Theory to ‘post-structural’ Political Economy and inhabiting a ‘post-Political Economy’ theoretical space – to the explanation of global agricultural change. This article examines Convention Theory (CT) as one such alternative approach, assessing its potential in the context of ongoing change within commercial organic agriculture in New Zealand. More specifically, CT is used to expose the insufficiency of recent ideas of conventionalisation and bifurcation, both reflecting more traditional Political Economic approaches, as explanatory concepts for the emerging condition of the New Zealand organic sector. In this paper, the concept of worlds of justification as developed in CT is utilised to address the emerging complexity of organic production. While farmers supplying a more diversified domestic market can be distinguished from those supplying export markets, an exclusive focus on such distinctions ignores the influential role of extra-economic factors on the viability of organic production systems. Thus, in addition to what are classified as market and industrial worlds in CT, the paper addresses aspects of civic, green, domestic, inspired and renown worlds. Producers' selections of organic certification organisations are used to demonstrate the interaction of these worlds in the development of the organic sector in New Zealand. The article concludes with the imperative to move ‘beyond bifurcation’ and acknowledge the greater complexity of negotiated outcomes that might be achieved from a CT perspective than from existing political economy-derived models like conventionalisation and bifurcation.     

Hierarchical related regression for combining aggregate and individual data in studies of socio-economic disease risk factors

Summary.  To obtain information about the contribution of individual and area level factors to population health, it is desirable to use both data collected on areas, such as censuses, and on individuals, e.g. survey and cohort data. Recently developed models allow us to carry out simultaneous regressions on related data at the individual and aggregate levels. These can reduce 'ecological bias' that is caused by confounding, model misspecification or lack of information and increase power compared with analysing the data sets singly. We use these methods in an application investigating individual and area level sociodemographic predictors of the risk of hospital admissions for heart and circulatory disease in London. We discuss the practical issues that are encountered in this kind of data synthesis and demonstrate that this modelling framework is sufficiently flexible to incorporate a wide range of sources of data and to answer substantive questions. Our analysis shows that the variations that are observed are mainly attributable to individual level factors rather than the contextual effect of deprivation.     

Email Effects on the Structure of Local Associations: A Social Network Analysis*

Objectives. This article explores the impact of email on the network structure of small, voluntary associations. By focusing on the density and centralization of associations, we illuminate how the Internet affects their cohesiveness and democratic character. Methods. Based on network data collected from 41 community‐based associations that are comparable on a variety of factors known to influence network structure, we employ multiple regression techniques to explore the impact of increased email use on group‐ and individual‐level network measures. Results. We find that the technological nature of email as well as the background, interests, and intentions of its users interact to influence density and centralization. Individuals employ electronic mail differently from other communication modes such as phone and face‐to‐face communication. Network density increases, and network centralization either increases or decreases, depending on the distribution of email use in the association. Conclusions. These effects on associational structure are likely to have significant long‐run impacts on the cohesion, efficacy, and democratic character of voluntary associations.     

Social class variation in risk: a comparative analysis of the dynamics of economic vulnerability1

A joint concern with multidimensionality and dynamics is a defining feature of the pervasive use of the terminology of social exclusion in the European Union. The notion of social exclusion focuses attention on economic vulnerability in the sense of exposure to risk and uncertainty. Sociological concern with these issues has been associated with the thesis that risk and uncertainty have become more pervasive and extend substantially beyond the working class. This paper combines features of recent approaches to statistical modelling of poverty dynamics and multidimensional deprivation in order to develop our understanding of the dynamics of economic vulnerability. An analysis involving nine countries and covering the first five waves of the European Community Household Panel shows that, across nations and time, it is possible to identify an economically vulnerable class. This class is characterized by heightened risk of falling below a critical resource level, exposure to material deprivation and experience of subjective economic stress. Cross‐national differentials in persistence of vulnerability are wider than in the case of income poverty and less affected by measurement error. Economic vulnerability profiles vary across welfare regimes in a manner broadly consistent with our expectations. Variation in the impact of social class within and across countries provides no support for the argument that its role in structuring such risk has become much less important. Our findings suggest that it is possible to accept the importance of the emergence of new forms of social risk and acknowledge the significance of efforts to develop welfare states policies involving a shift of opportunities and decision making on to individuals without accepting the ‘death of social class’ thesis.     

Robust Confidence Intervals for Regression Parameters

The paper considers the problem of finding accurate small sample confidence intervals for regression parameters. Its approach is to construct conditional intervals with good robustness characteristics. This robustness is obtained by the choice of the density under which the conditional interval is computed. Both bounded influence and S-estimate style intervals are given. The required tail area computations are carried out using the results of DiCiccio, Field & Fraser (1990).     

Perceived Marginalization and the Prediction of Romantic Relationship Stability

The present research examined how perceived marginalization of one’s romantic relationship is associated with level of future commitment to and stability of that involvement. Results from a 7‐month longitudinal study of romantically involved individuals (N= 215) revealed that perceived social network marginalization at Time 1 predicted breakup status at Time 2, with commitment level at Time 1 fully mediating this association. Among those individuals whose relationships remained intact, social network marginalization predicted Time 2 commitment above and beyond satisfaction, alternatives, and investments. Additional analyses revealed that perceived general societal marginalization was a less robust predictor of relationship commitment and stability compared to social network marginalization. These findings highlight the important consequences of perceived social disapproval on relationship outcomes.     

Great Expectations?: The Dubious Financial Legacy of Quality Audits

In recent years there appears to have been a veritable boom in the provision of ‘quality audits’– that is, audits of organizations' production processes and management systems. Despite the rising significance of this international audit movement affecting hundreds of thousands of organizations world‐wide, there has been limited interest in, or critique of, the practice of quality audit by academic auditing researchers. This paper traces the history of quality assurance standards and auditing and finds that quality auditing is not simply an outgrowth of an engineering inspection function. Rather, for several decades, quality auditors have consciously modelled their practice on that of the statutory financial audit, which in turn, exposes them to similar issues with regard to the long standing ‘expectations gap’ debate. Yet, despite what the authors argue are critical links with the financial audit, there has not been any notable involvement on the part of the accounting profession with quality auditing. The growing demand for ‘added‐value’ audits poses considerable questions for the future development and organizational significance of quality auditing. Current developments in both quality and financial audit services suggest that these two influential audit movements are now competing against each other to promote business excellence and contribute to business strategy.