Still-births among the offspring of male radiation workers at the Sellafield nuclear reprocessing plant: detailed results and statistical aspects

Summary. This study investigates whether there was evidence of increasing risk of still-birth with increasing paternal exposure to ionizing radiation received during employment at the Sellafield nuclear installation before the child was conceived. A significant positive association is found between the total paternal preconceptional exposure to external ionizing radiation and the risk of still-birth (after adjustment for year of birth, social class, birth order and paternal age, odds ratio at 100 mSv 1.24 (95% confidence interval 1.04–1.45)). A summary of the principal scientific findings of this study has been published in the Lancet . This paper describes in detail the statistical methods that were used in the investigation and presents the results in full.     

Cohort Succession in the US Housing Market: New Houses, the Baby Boom, and Income Stratification

Federal housing policy in the US across the postwar period supported the construction of new houses more than public provision or renovation of older structures as a means of ensuring a sufficient supply of quality dwellings. Understanding trends in new housing in particular is thus crucial to understanding the housing regime. Following Myers (Housing demography: Linking demographic structure and housing markets. University of Wisconsin Press, 1990; Housing Studies, 14, 473–490,1999), this paper conceptualizes historical change in the housing stock within a demographic framework as the movement of cohorts of households through cohorts of housing stock. Recent evidence suggests that a new cohort of houses arose in the 1980s and 1990s (larger with more amenities than past vintages), and that buyers of those new houses were increasingly affluent. In this paper, I link the succession to a new cohort of houses to household cohort succession and examine the increasing affluence of new house buyers by age and cohort, focusing especially on the entry of the Baby Boom generation exactly when the new cohort of houses arrived. I use US Census microdata for 1960–2000 to develop a cohort longitudinal dataset, and analyze historical change in stratification in new house ownership. I find significant shifts between cohorts in income inequality among new house buyers, with implications for the capacity of the housing regime to meet the future needs of an increasingly diverse population.

深度老龄化对我国劳动就业的潜在影响

对我国就业人口现状,2000-2010年城市、城镇、乡村人口就业速度,我国三大产业就业人口变化及人口年龄组劳动参与率变化的研究表明:若退休年龄不变,2030年我国潜在劳动力将比2010年减少14%;若男女退休年龄分别推迟5年,则2030年潜在劳动力仍将与2010年相当。然而,青年劳动力的比例下降快,农村尤其明显;2020年以后我国劳动力递减速度快,2040年我国60岁以上、65岁以上和80岁以上老年人口比例将超过28%、22%和4%。近20年我国经济发展很快,但面临老龄化的严重挑战,老龄化通过劳动力老化、社会保障、生产成本、商品出口、社会消费、货币汇率等途径,对经济持久地产生影响。     

Bayesian Forecasting With Stable Seasonal Patterns

A multiplicative seasonal forecasting model for cumulative events in which, conditional on end- of-season totals being given and seasonal shape being known, it is shown that events occurring within the season are multinomially distributed is presented. The model uses the information contained in the arrival of new events to obtain a posterior distribution for end-of-season totals. Bayesian forecasts are obtained recursively in two stages: first, by predicting the expected number and variance of event counts in future intervals within the remaining season, and then by predicting revised means and variances for end-of-season totals based on the most recent forecast error.     

Pseudo Panel Data Models With Cohort Interactive Effects

When genuine panel data samples are not available, repeated cross-sectional surveys can be used to form so-called pseudo panels. In this article, we investigate the properties of linear pseudo panel data estimators with fixed number of cohorts and time observations. We extend standard linear pseudo panel data setup to models with factor residuals by adapting the quasi-differencing approach developed for genuine panels. In a Monte Carlo study, we find that the proposed procedure has good finite sample properties in situations with endogeneity, cohort interactive effects, and near nonidentification. Finally, as an illustration the proposed method is applied to data from Ecuador to study labor supply elasticity. Supplementary materials for this article are available online.     

Predictors of child protective service contact between birth and age five: An examination of California's 2002 birth cohort

This study utilizes population-level birth data to describe those children who may be at greatest risk of maltreatment during the first five years of life. Based on a unique dataset constructed by linking California's administrative child welfare data to statewide vital birth records, a cohort study design was employed to track reports of maltreatment involving children born in 2002. Twelve variables captured in the birth record were selected for analysis. Generalized Linear Models were used to estimate adjusted risk ratios (RR) for each independent variable. Predicted probabilities of CPS contact were computed based on the count of risk factors present at birth. Results suggest that many of the associations previously observed between birth variables and subsequent maltreatment have sustained value in foretelling which children will be reported to CPS beyond infancy. Of the 531,035 children born in California in 2002, 14% (74,182) were reported for possible maltreatment before the age of five. Eleven of the twelve birth variables examined presented as significant predictors of contact with child protective services.     

Analysis of the Bovine Spongiform Encephalopathy Maternal Cohort Study: Evidence for Direct Maternal Transmission

In an initial exploratory analysis of the bovine spongiform encephalopathy (BSE) maternal cohort study data we demonstrate several confounding effects in the study design. Given these effects, we assess a variety of statistical models to determine the relative contributions of direct maternal transmission of the aetiological agent of BSE and of genetic susceptibility to the observed maternally enhanced risk of BSE in the offspring of affected dams. To control for the substantial between-herd variation in the risk of exposure to the BSE agent, it is essential that analyses take into account the matched pair structure of the data. Maternal exposure is estimated to be most important in animals born within 150 days of disease onset in their dams. The analysis of a full survival likelihood model indicates that the hypothesis of maternal transmission with no genetic variation in susceptibility fits the data significantly better than the hypothesis of genetically variable susceptibility with no maternal transmission. However, models incorporating both maternal transmission and genetically variable susceptibility fit the data significantly better than pure maternal transmission models. Although genetic susceptibility cannot be excluded as the cause of the cohort study results in the absence of detailed genotyping, the analysis of these study data suggest that low level maternal transmission of BSE is, at least in part, responsible for the significantly enhanced risk of BSE in the offspring of affected dams. Similar results indicating significant maternal transmission in the later stages of the dam incubation period are obtained from the independent analysis of data on the dam–offspring relationships among confirmed BSE cases.     

Analysis of the Bovine Spongiform Encephalopathy Maternal Cohort Study: the Discordant Case–Control Pairs

The progeny of the affected and non-affected dams in the bovine spongiform encephalopathy (BSE) cohort study were paired in terms of their farm of origin and approximate date of birth. This paper presents an exact logistic regression analysis that avoids modelling the differences between the pairs and so analyses only the discordant pairs. There is some evidence that the pairs in which the affected animal was born to the affected dam tend to be those in which the onset of BSE in the affected dam preceded or occurred soon after the calving. This suggests some occurrence of maternal transmission.     

Design priorities and disciplinary perspectives: the case of the US National Children's Study

Summary.  The National Children's Study (NCS), which was undertaken in 2000 by collaboration between several US federal government agencies, is one of the largest and boldest longitudinal studies of children's health ever undertaken. One of the key design issues has been the nature of the NCS sample. The paper describes the nature of the choices and the reasons for the decision that the NCS be based on a national probability sample. Designed as a study of the environmental influences on children's health and development, the NCS is expected to identify, enrol and follow about 100000 children from their birth to the age of 21 years. A broad definition of relevant environments of interest, and a full partnership between government, university and medical scientists, introduces considerable challenges in the design of the study.     

Comparison of labour and birth outcomes between nulliparous women who used epidural analgesia in labour and those who did not: A prospective cohort study

ObjectiveTo compare labour and birth outcomes between nulliparous women who used versus did not use intrapartum epidural analgesia.DesignProspective cohort study.SettingTwo maternity hospitals in Ireland.PopulationA total of 1221 nulliparous women who gave birth vaginally or by emergency caesarean section.MethodsMultinomial logistic regression was used to analyse categorical outcomes, with results presented as ratios of relative risks (RRR). For dichotomous outcomes we used logistic regression, with results presented as odds ratios (OR).Main outcome measuresMode of birth, IV syntocinon use, pyrexia (≥38 °C), antibiotic treatment, first stage labour ≥10 h, second stage labour ≥2 h, blood loss (≥500 mls, ≥1000 mls), perineal trauma. Neonatal outcomes included Apgar score ≥7 at 1 min and 5 min, admission to neonatal intensive care unit, and infant feeding method.ResultsWomen using EA were more likely to require a vacuum-assisted birth (RRR 3.35, p < 0.01) or forceps-assisted birth (RRR 11.69, p < 0.01). Exposure to EA was associated with significantly greater risk of ≥10 h first (OR 6.72, p = 0.01) and ≥2 h second (OR 2.25, p < 0.01) stage labour, increased likelihood of receiving IV syntocinon (OR 9.38, p < 0.01), antibiotics (OR 2.97, p < 0.01) and a greater probability of pyrexia (OR 10.26, p < 0.01). Women who used EA were half as likely to be breastfeeding at three months postpartum (OR 0.53, p < 0.01). No differences were observed between groups in neonatal outcomes.ConclusionsOur data shows significant associations between EA use and several intrapartum outcomes.