Demographic Determinants of Infant and Early Child Mortality: A Comparative Analysis

In this paper we examine the relative importance of a number of demographic determinants of infant and early child mortality using information from 39 World Fertility Survey countries. We include sex of the child, age of the mother at the time of the birth, birth order, mother's educational level and a number of indicators of spacing of adjacent births among the correlates of chances of survival for children below the age of five years. Mortality of firstborn children and of those born to teenage mothers is shown to be higher than average; that of later children and those of older mothers was not much higher than average, once other factors are controlled. Effects of poor birth-spacing persist even after other factors have been controlled, and are similar where a sib was born during the two years preceding the birth of the child, regardless of the survival status of that sib; however, mortality was higher when that sib had died, due to increased familial risks of mortality. Rapid subsequent births also raise mortality for their earlier sibs. The findings are generally remarkably consistent in a wide range of countries and associated mortality conditions, although attention is drawn to a few interesting geographically clustered exceptions which deserve further investigation. The study leaves little room for doubt that poor child-spacing is clearly linked to decreased survival chances.     

A framework for production rescheduling in sociotechnical manufacturing environments

No plan survives contact with reality. Despite the rich research base regarding handling uncertainty in production planning and control systems, there is an intellectual gap between theory and practice with regard to handling unforeseen events generated by internal and external factors, such as unforeseen machine downtimes and changes in demand. Motivated by longitudinal observations in two industrial settings and an analysis of the relevant literature, a framework for rescheduling decision-making in the face of unforeseen production events is proposed. In practical settings, the effectiveness of decisions depends on a set of situational factors. The findings of this research can be utilised further to provide guidelines for developing effective decision support principles and systems, addressing the needs of organisational decision-makers.     

FEMA and the Witt Revolution: Testing the Hypothesis of “Bureaucratic Autonomy”

In the wake of widespread criticism for its poor performance in Hurricane Andrew in 1992, FEMA became a more effective organization under the leadership of James Witt (1993–2001). One answer to the question of how and why FEMA improved so rapidly and significantly during this period is Carpenter’s (2001) theory of “bureaucratic autonomy.” This paper defines the minimum conditions Carpenter considers necessary for the term, evaluates their applicability to FEMA during this period, and briefly examines alternative explanations for FEMA’s organizational transformation. It concludes that the innovation and entrepreneurship FEMA demonstrated during this period do indeed meet the criteria for “bureaucratic autonomy.”

Estimating stage occupation probabilities in non-Markov models

We study non-Markov multistage models under dependent censoring regarding estimation of stage occupation probabilities. The individual transition and censoring mechanisms are linked together through covariate processes that affect both the transition intensities and the censoring hazard for the corresponding subjects. In order to adjust for the dependent censoring, an additive hazard regression model is applied to the censoring times, and all observed counting and “at risk” processes are subsequently given an inverse probability of censoring weighted form. We examine the bias of the Datta–Satten and Aalen–Johansen estimators of stage occupation probability, and also consider the variability of these estimators by studying their estimated standard errors and mean squared errors. Results from different simulation studies of frailty models indicate that the Datta–Satten estimator is approximately unbiased, whereas the Aalen–Johansen estimator either under- or overestimates the stage occupation probability due to the dependent nature of the censoring process. However, in our simulations, the mean squared error of the latter estimator tends to be slightly smaller than that of the former estimator. Studies on development of nephropathy among diabetics and on blood platelet recovery among bone marrow transplant patients are used as demonstrations on how the two estimation methods work in practice. Our analyses show that the Datta–Satten estimator performs well in estimating stage occupation probability, but that the censoring mechanism has to be quite selective before a deviation from the Aalen-Johansen estimator is of practical importance. N. Gunnes—Supported by a grant from the Norwegian Cancer Society.     

Efficient construction of reversible jump Markov chain Monte Carlo proposal distributions

Summary. The major implementational problem for reversible jump Markov chain Monte Carlo methods is that there is commonly no natural way to choose jump proposals since there is no Euclidean structure in the parameter space to guide our choice. We consider mechanisms for guiding the choice of proposal. The first group of methods is based on an analysis of acceptance probabilities for jumps. Essentially, these methods involve a Taylor series expansion of the acceptance probability around certain canonical jumps and turn out to have close connections to Langevin algorithms. The second group of methods generalizes the reversible jump algorithm by using the so-called saturated space approach. These allow the chain to retain some degree of memory so that, when proposing to move from a smaller to a larger model, information is borrowed from the last time that the reverse move was performed. The main motivation for this paper is that, in complex problems, the probability that the Markov chain moves between such spaces may be prohibitively small, as the probability mass can be very thinly spread across the space. Therefore, finding reasonable jump proposals becomes extremely important. We illustrate the procedure by using several examples of reversible jump Markov chain Monte Carlo applications including the analysis of autoregressive time series, graphical Gaussian modelling and mixture modelling.     

Sexual Behavior in China: Trends and Comparisons

Dramatic political, economic, and social changes in China over the past several decades have been accompanied by much discussion in popular media and among academics of a fundamental transformation in Chinese sexual behavior. Several studies have examined current Chinese sexual behavior but have been limited to particular provinces or cities and have been based on non‐random samples. The potential threat of a generalized HIV epidemic in China highlights the dearth of population‐based information on current patterns of sexual behavior that could help design better intervention strategies and prevent misguided ones. This article uses data from the first national probability survey of adult sexual behavior in China completed during 1999–2000, along with a historical and literature review, to address three key questions: 1) Has there been a revolution in sexual behavior in China? 2) Is China unique compared to other countries in these transformations? 3) What are the implications of these findings for China's risk of a generalized HIV epidemic?     

Public Accounts: Defending Contested Practices

Little attention has been paid to how actors account for controversial institutional conduct or contested practices. Relying on a content analysis of letters to the editor, I explore how actors operating in the Habermasian “public sphere” justify the contested practice of linking Native American symbols with sports teams, and suggest that in their rejection of challengers to their definitions of the situation, authors create public accounts. Consisting primarily of justifications rather than excuses, these accounts are of four types: “denial of injury,” “assertion of benefit,” “claim of authority,” and “rejection of challenge.” For those who wish to conduct comparative analyses of contested practices, these concepts may prove useful.     

Cryptosporidium and Dairy Cattle in the Catskill/Delaware Watershed: A Quantitative Risk Assessment

We carried out a study to estimate the public health risk posed by dairy cattle located in New York City's Catskill/Delaware watershed, as measured by daily C. parvum-like oocyst loading. A Monte Carlo simulation model that takes into account the nature of the dairy cattle population within the target area, age-specific incidence/prevalence rates, as well as differential fecal production and oocyst-shedding intensity rates was used to address the objectives. Additionally, the model was designed to distinguish between zoonotic and nonzoonotic species/genotypes of Cryptosporidium. Total estimated daily C. parvum-like oocyst shedding across all age/production categories was estimated at 4.15 x 10(10). The zoonotic C. parvum comprised 93.5% of this load. It was estimated that preweaned calves produce 99.5% of the total daily C. parvum ocyst burden. The recently described nonzoonotic C. bovis was estimated to have a daily load of 2.2 x 10(9) oocysts across all age/production strata. C. parvum deer-like genotype was estimated to have a total daily load of 1.3 x 10(9) oocysts. The results of this study support earlier assertions that strategies aimed at reducing the cryptosporidial risk posed by dairy cattle to public health will be most efficacious if aimed at preweaned calves.