Nonparametric estimation in the illness-death model using prevalent data

We study nonparametric estimation of the illness-death model using left-truncated and right-censored data. The general aim is to estimate the multivariate distribution of a progressive multi-state process. Maximum likelihood estimation under censoring suffers from problems of uniqueness and consistency, so instead we review and extend methods that are based on inverse probability weighting. For univariate left-truncated and right-censored data, nonparametric maximum likelihood estimation can be considerably improved when exploiting knowledge on the truncation distribution. We aim to examine the gain in using such knowledge for inverse probability weighting estimators in the illness-death framework. Additionally, we compare the weights that use truncation variables with the weights that integrate them out, showing, by simulation, that the latter performs more stably and efficiently. We apply the methods to intensive care units data collected in a cross-sectional design, and discuss how the estimators can be easily modified to more general multi-state models.     

Theory and practice in teaching evaluation of intervention outcomes

This paper describes a course in the evaluation of intervention outcomes which combines classroom instruction with practical field work. The course was part of the BA programme in the Bob Shapell School of Social Work at Tel-Aviv University. It was given in conjunction with an advanced course in social work methods, and it entailed the active participation of the evaluation instructor, the methods instructor, and the fieldwork supervisor. To attain this integration, it was necessary not only to design the course but also to invest in training field supervisors, who could then serve as a resource for their students.

The paper emphasises the importance of cooperation between all those involved in teaching the course as well as the special significance of teaching the subject as part of the socialisation process of social work students. It also points out the various benefits both the students and instructors obtained from the course.     

From the ‘Double Nature’ of Cooperation to the Social Economy: Fifty Years of Associationalism1

The past 50 years or so have witnessed significant changes in the way of conceiving and practising cooperation. Three major shifts are presented here: (1) from the single to the multi-stakeholder cooperative; (2) from internal to extended mutuality in cooperatives and (3) from the historical ‘double nature’ of cooperation to the social economy. It is argued that these shifts testify of the capability of the cooperative system to adapt to such global trends as privatization, deregulation and ‘tertiarization’ that came in the wake of globalization. Moving from the traditional model of the single stakeholder cooperative based on internal homogeneity and on the identification of the notion of member and user, to a new model of multi-stakeholder organization, broadened the scope of cooperatives yet, at the same time, sharpened the socio-economic tension at the inter-cooperative level. Hence, the need, for cooperatives, to strengthen their links with similar nonprofit organizations as partners in the social economy. Our approach is grounded on a Western European interpretation of cooperatives, although the social economy is recently making strides outside Europe, especially in Canada and Latin America.     

Motor Function and Social Participation in Kindergarten Children

This study focused on the associations between individual variations in children’s motor abilities and individual differences in social participation and play behavior. Indoor and outdoor play behavior patterns of 88 kindergarten children were observed, and a battery of standard assessments of basic motor functions was administered. The findings indicate significant associations between children’s motor abilities and social and nonsocial forms of play. Results are discussed in relation to existing conceptual models of the underlying causes for nonsocial behavior.     

Public Servants’ Trust in Citizens: An Extension of Theory and an Empirical Examination with Structural Equation Modeling (SEM)

This study examined trust that public servants have in citizens. We build on the reciprocal nature of trust and applied Structural Equation Modeling (SEM) to test both the antecedents to public servants?? trust in citizens (e.g., job satisfaction, organizational commitment, organizational politics, public sector motivation and generalized trust) and several of its potential outcomes (exit, voice, loyalty, neglect and cynicism) among Israeli civic servants. A revised and improved model found that organizational politics and generalized trust are the strongest predictors of public servants?? trust in citizens and that exit intention is its major outcome. Implications and suggestions for future studies are presented.     

Quantitative Assessment of the Risk of Release of Foot‐and‐Mouth Disease Virus via Export of Bull Semen from Israel

Various foot‐and‐mouth disease (FMD) virus strains circulate in the Middle East, causing frequent episodes of FMD outbreaks among Israeli livestock. Since the virus is highly resistant in semen, artificial insemination with contaminated bull semen may lead to the infection of the receiver cow. As a non‐FMD‐free country with vaccination, Israel is currently engaged in trading bull semen only with countries of the same status. The purpose of this study was to assess the risk of release of FMD virus through export of bull semen in order to estimate the risk for FMD‐free countries considering purchasing Israeli bull semen. A stochastic risk assessment model was used to estimate this risk, defined as the annual likelihood of exporting at least one ejaculate of bull semen contaminated with viable FMD virus. A total of 45 scenarios were assessed to account for uncertainty and variability around specific parameter estimates and to evaluate the effect of various mitigation measures, such as performing a preexport test on semen ejaculates. Under the most plausible scenario, the annual likelihood of exporting bull semen contaminated with FMD virus had a median of 1.3 * 10^?7 for an export of 100 ejaculates per year. This corresponds to one infected ejaculate exported every 7 million years. Under the worst‐case scenario, the median of the risk rose to 7.9 * 10^?5, which is equivalent to the export of one infected ejaculate every 12,000 years. Sensitivity analysis indicated that the most influential parameter is the probability of viral excretion in infected bulls.