Multilevel Latent Class Models

The latent class (LC) models that have been developed so far assume that observations are independent. Parametric and nonparametric random–coefficient LC models are proposed here, which will make it possible to modify this assumption. For example, the models can be used for the analysis of data collected with complex sampling designs, data with a multilevel structure, and multiple–group data for more than a few groups. An adapted EM algorithm is presented that makes maximum–likelihood estimation feasible. The new model is illustrated with examples from organizational, educational, and cross–national comparative research.     

Examining the Impact of Changes in Maternal Employment on High School Completion Among Low-Income Youth

The passage of the Personal Responsibility and Work Opportunity Reconciliation Act and decisions about its re-authorization have resurrected interest in the impact of maternal employment on child outcomes in poor families. The emerging evidence suggests that employment stability among former welfare recipients is a key factor in making successful transitions from welfare to work. This investigation explores how changes in maternal employment in poor families relate to high school completion among at risk youths. Our findings show that a substantial number of mothers experience unstable employment patterns. This instability is positively correlated with dropout among adolescents. The paper concludes with policy implications for the next phase of welfare reform.     

Estimation of the intercept parameter for linear regression model with uncertain non-sample prior information

This paper considers alternative estimators of the intercept parameter of the linear regression model with normal error when uncertain non-sample prior information about the value of the slope parameter is available. The maximum likelihood, restricted, preliminary test and shrinkage estimators are considered. Based on their quadratic biases and mean square errors the relative performances of the estimators are investigated. Both analytical and graphical comparisons are explored. None of the estimators is found to be uniformly dominating the others. However, if the non-sample prior information regarding the value of the slope is not too far from its true value, the shrinkage estimator of the intercept parameter dominates the rest of the estimators.     

A comparison study of realtime fatality rates: severe acute respiratory syndrome in Hong Kong, Singapore, Taiwan, Toronto and Beijing, China

Summary.  In an outbreak of a completely new infectious disease like severe acute respiratory syndrome (SARS), estimation of the fatality rate over the course of the epidemic is of clinical and epidemiological importance. In contrast with the constant case fatality rate, a new measure, termed the 'realtime' fatality rate, is proposed for monitoring the new emerging epidemic at a population level. A competing risk model implemented via a counting process is used to estimate the realtime fatality rate in an epidemic of SARS. It can capture and reflect the time-varying nature of the fatality rate over the course of the outbreak in a timely and accurate manner. More importantly, it can provide information on the efficacy of a certain treatment and management policy for the disease. The method has been applied to the SARS data from the regions affected, namely Hong Kong, Singapore, Toronto, Taiwan and Beijing. The magnitudes and patterns of the estimated fatalities are virtually the same except in Beijing, which has a lower rate. It is speculated that the effect is linked to the different treatment protocols that were used. The standard estimate of the case fatality rate that was used by the World Health Organization has been shown to be unable to provide useful information to monitor the time-varying fatalities that are caused by the epidemic.     

Complexity Theory and Strategic Change: an Empirically Informed Critique*

We present a four‐year ethnographic study of a public‐sector organization and use narrative to describe its development in terms of four complexity theory concepts: sensitivity to initial conditions, negative and positive feedback processes, disequilibrium and emergent order. Our study indicates that order emerges at the boundary between the organization's legitimate and shadow systems. We suggest that the underlying dynamic leading to the emergent order is the need to reduce anxiety. Our findings cause us to question the assertion that organizations are naturally complex adaptive systems producing novel forms of order. We propose an alternate view that in social systems, equilibrium‐seeking behaviour is the norm; such systems can self‐organize into hierarchy. We draw attention to some of the difficulties we found in applying complexity‐theory concepts to a social system and conclude by advocating the development of complexity theory through the incorporation of insights from psychology and social theory.     

Reports of Conferences, Institutes, and Seminars

Reports on the 2005 North Carolina Serials Conference, the twentieth anniversary conference of the North American Serials Interest Group, the 2005 Acquisitions Institute at Timberline Lodge, and a program on electronic archiving sponsored by the New England Chapter of the Association of College and Research Libraries.     

SEXUAL PRIVACY AND EARLY SEXUAL DEBUT IN NAIROBI INFORMAL SETTLEMENTS1

The purpose of this paper is to examine sexual privacy as a factor that may influence the relatively earlier sexual debut among the urban poor in Nairobi. 40 focus group discussions were held with people aged 13–17, 18–24, 25–49 and 50+ years, community leaders and service providers in four informal settlements of Nairobi. Lack of sexual privacy was identified as a major problem. Although adults were reported to use various means to acquire some measure of privacy, such as waiting for children to fall asleep, switching off the lights and separating the sleeping areas using curtains, these measures were found inadequate. The participants therefore associated young people's early initiation of sexual activity with lack of sexual privacy. Sexual privacy has not received adequate research attention as a dimension of poverty that influences young people's sexuality. More studies are called for to unravel the specific association between sexual privacy among adults and young people's sexual behaviour. The living conditions of the urban poor should also be addressed to mitigate the effects of lack of sexual privacy.     

CHANGING FAMILIES/CHANGING COMMUNITIES

Scholars writing about community in recent years have been more likely to lament its passing than celebrate its exemplars. What's missing in this recent revival of interest in community is a systematic link with work–family issues and, in particular, an explicit recognition that women's and men's work–family lives have changed dramatically in the post-World War II era. We investigate the consequences of structural shifts in our family and work lives for a sample of elite, managerial women in dual-earner marriages, a population for whom work and family concerns are both immediate and salient. Understanding changing definitions of, and trends in, family and work can provide a useful lens through which we can profitably address recent debates about the decline or resurgence of community and civic society. Our findings suggest that, although conceived differently than in previous decades, family remains central to our respondents’ sense of community and structures their civic engagement. In contrast with previous generations of women, however, work is also important, for defining women's sense of self and community and for offering an alternative venue for community service.