Children and their child care caregivers: profiles of relationships

One thousand three hundred and seventy-nine (682 girls) caregiver-child relationships were used to derive attachment behavior profiles. All of the children were enrolled in child care (72% in child care centers). Profile analysis was completed using five subscales of Attachment Q-Set items. Three profiles were replicated on randomly drawn subsamples, on center based and in-home based subsamples and on separate subsamples of toddler and preschool children. These profiles were labeled: difficult, avoiding and secure. Children in the secure profile had higher security scores than children in the difficult or avoiding profiles. Children in the avoiding profile appeared the most heterogeneous in attachment security. Children in the avoiding profile with high as opposed to low security scores were older and more likely to use the caregiver as a secure base, seek her for comfort and engage in positive negotiations. Observations conducted on the children with their caregivers provided external validity for the profiles. Children in the secure profile had the most adult involvement.     

A Bayes-type estimator for the Bradley-Terry model for paired comparison

A Bayes-type estimator is proposed for the worth parameter π_i and for the treatment effect parameter ln π_i in the Bradley-Terry Model for paired comparison. In contrast to current Bayes estimators which require iterative numberical calculations, this estimator has a closed form expression. This estimation technique is also extended to obtain estimators for the Luce Multiple Comparison Model. An application of this technique to a 2³ factorial experiment with paired comparisons is presented.     

Housing as Health Capital: How Health Trajectories and Housing Paths Are Linked

This article explores the relationships between housing and health inequalities. It locates housing within a network of health resources that can either promote well-being or increase susceptibility to disease. Housing thereby contributes to the accumulation, or depletion, of the health capital of individuals and communities. Qualitative interviews in three British regions help specify the links between health capital, on the one hand, and the network of resources, environments, events, institutions, and social relations comprising the housing system, on the other. The findings show why, from a health capital/health-resources-network perspective, a segment of the housing system (owner-occupation) that generally appears therapeutic can have the opposite effect for people whose resilience is low or whose health is in decline .     

Linked lives,dependent demise? Survival analysis of husbands and wives

Past research has found that married individuals have substantially lower risks of mortality than their single counterparts. This paper examines how household characteristics affect spouses’ risks of mortality. A paired hazard rate model is estimated and tests are made to ascertain whether the estimated coefficients associated with risk factors differ between husbands’ and wives’ equations. Cigarette smoking, risk-avoidance behavior, poverty, and children are found to affect wives’ and husbands’ mortality in similar ways. Divorce, which can be interpreted as the termination of this shared household environment, is found to affect spouses differently.     

Variance Estimation in Spatial Regression Using a Non-parametric Semivariogram Based on Residuals

Abstract.  The empirical semivariogram of residuals from a regression model with stationary errors may be used to estimate the covariance structure of the underlying process. For prediction (kriging) the bias of the semivariogram estimate induced by using residuals instead of errors has only a minor effect because the bias is small for small lags. However, for estimating the variance of estimated regression coefficients and of predictions, the bias due to using residuals can be quite substantial. Thus we propose a method for reducing this bias. The adjusted empirical semivariogram is then isotonized and made conditionally negative-definite and used to estimate the variance of estimated regression coefficients in a general estimating equations setup. Simulation results for least squares and robust regression show that the proposed method works well in linear models with stationary correlated errors.     

Infant Exposure Assessment for Breast Milk Dioxins and Furans Derived from Waste Incineration Emissions

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) have been detected in human milk samples obtained in several countries. Possible sources include emissions from incineration of municipal waste in resource recovery facilities. A formula is presented for calculating the infant daily dose of dioxin equivalents from breast milk on the basis of the maternal daily intake. Application of the formula suggests that an infant breast-fed for 12 months would receive around 10% of the cumulative exposure dose per body weight that would be received by an adult with 50 years of exposure. Further analysis indicated that the contribution of dioxin equivalents from breast milk to an infant's body concentration at the end of 12 months of breast feeding would amount to 1.7 times the concentration in the mother. However, dioxin and furan emissions from a source calculated to result in worst-case lifetime cancer risks of the order of 1 in 100,000 are only likely to increase breast milk concentrations by around 1%-10% of the levels that have been detected in several countries. This finding suggests that there are major sources of dioxins and furans other than from municipal solid waste incineration that need to be identified.     

Diagnosis Murder: The Death of State Death Taxes

Since 1976, more than 30 states have eliminated their "death" taxes and many others have reduced them. This unexplored case of interstate tax competition presents a unique opportunity to develop a new, more satisfying definition of competitor based on historical elderly migration patterns. Using data from 1967 onward, we outline the recent history of state death tax competitio n and present a spatial econometric analysis. Interstate tax competition is evident and grows stronger when using migration-based definitions of competitors. The article concludes with still more evidence of interstate tax competition—the recent movement by states to effectively revive their death taxes.     

Repeated‐measures models in the analysis of QT interval

Because of the recent regulatory emphasis on issues related to drug‐induced cardiac repolarization that can potentially lead to sudden death, QT interval analysis has received much attention in the clinical trial literature. The analysis of QT data is complicated by the fact that the QT interval is correlated with heart rate and other prognostic factors. Several attempts have been made in the literature to derive an optimal method for correcting the QT interval for heart rate; however the QT correction formulae obtained are not universal because of substantial variability observed across different patient populations. It is demonstrated in this paper that the widely used fixed QT correction formulae do not provide an adequate fit to QT and RR data and bias estimates of treatment effect. It is also shown that QT correction formulae derived from baseline data in clinical trials are likely to lead to Type I error rate inflation. This paper develops a QT interval analysis framework based on repeated‐measures models accomodating the correlation between QT interval and heart rate and the correlation among QT measurements collected over time. The proposed method of QT analysis controls the Type I error rate and is at least as powerful as traditional QT correction methods with respect to detecting drug‐related QT interval prolongation. Copyright © 2003 John Wiley & Sons, Ltd.