Tests and Confidence Intervals for an Extended Variance Component Using the Modified Likelihood Ratio Statistic

Abstract.  The large deviation modified likelihood ratio statistic is studied for testing a variance component equal to a specified value. Formulas are presented in the general balanced case, whereas in the unbalanced case only the one-way random effects model is studied. Simulation studies are presented, showing that the normal approximation to the large deviation modified likelihood ratio statistic gives confidence intervals for variance components with coverage probabilities very close to the nominal confidence coefficient.     

Where angels fear to tread: Richard Schoenherr (1935–1996)

Richard Schoenherr, professor of sociology at the University of Wisconsin — Madison, passed away unexpectedly on 9 January 1996. He is memorialized in this essay for his scholarly contributions in the areas of teaching, research, and service.     

Does Family Structure Matter in the Relationships Between Youth Assets and Youth Alcohol,Drug and Tobacco Use?

This study investigated significant relationships between youth assets and youth alcohol, tobacco, and drug use that differ according to family structure (one- or two-parent households). Data were collected from a randomly sampled inner-city population (n=1,256 teenagers and 1,256 parents of the teenagers) using in-home, in-person interviews. Logistic regression analyses, stratifying by one- and two-parent household status, were conducted with nine youth assets as the independent variables and youth alcohol, tobacco, and drug use as the dependent variables. Results indicated that the associations between assets and risk behaviors varied depending upon whether the youth lived in one- or two-parent households. Continued research is warranted to further investigate associations among family structure, youth assets, and youth risk behaviors.     

Interparental Conflict and Preschoolers' Peer Relations: The Moderating Roles of Temperament and Gender

The relations between destructive interparental conflict (IPC) and three‐ to six‐year‐olds’ (N = 62) peer relations were examined as a function of child temperament and gender. Regression analyses indicated that effortful control moderated the relations of IPC with children's amount of peer interaction as well as with their problematic relations with peers. Specifically, high IPC was associated with low amount of interaction and high problematic relations for preschoolers low in effortful control, but it was related to high amount of interaction and low problems for those high in effortful control. Additionally, gender differences in the relations between IPC and the amount of peer interaction indicated that IPC was negatively related to the amount of interaction for girls but positively related to the amount for boys. The findings highlight the need for examining individual differences in the relations between IPC and the development of early peer relations.     

The Effect of School Quality on Black-White Health Differences: Evidence From Segregated Southern Schools

This study assesses the effect of black-white differences in school quality on black-white differences in health in later life resulting from the racial convergence in school quality for cohorts born between 1910 and 1950 in southern states with segregated schools. Using data from the 1984–2007 National Health Interview Surveys linked to race-specific data on school quality, we find that reductions in the black-white gap in school quality led to modest reductions in the black-white gap in disability.     

Alcohol Consumption and Cirrhosis Mortality in the Industrialised Countries Since 1950

Before 1975 or 1980, there was a substantial increase in the consumption of alcohol throughout the industrialised countries. Thereafter, trends in the various countries began to diverge. In the Mediterranean countries and the Anglo-Saxon countries bordering the Pacific, consumption underwent a decline; it remained relatively stable in most of the Central and Northern European countries, whilst in the former socialist countries and certain Northern European countries, it continued to rise. Cirrhosis mortality has followed changes in the consumption trends of the main alcoholic beverage or that of spirits (when a certain consumption threshold is exceeded). Before 1980, the increase in alcohol consumption primarily involved men and, today, excess male mortality is higher than it was forty years ago, despite a slight convergence between male and female mortality rates. In several North or Central European countries, excessive alcohol consumption is presently slowing down the decline of the general death rates. In Eastern Europe, it is one of the basic factors responsible for the stagnation or even upturn of mortality rates.     

The influence of riparian corridor width on ant and plant assemblages in northern Sydney,Australia

Protecting riparian corridors is a commonly applied environmental policy in urban landscapes. However, empirical data demonstrating their efficacy for biodiversity conservation outcomes is scarce. In this study we investigated whether riparian corridor width influences the diversity and community structure of ant (Hymenoptera: Formicidae) and vascular plant assemblages therein. Eighteen corridors of differing widths were selected from within the Ku-ring-gai Local Government Area, Sydney Australia. Ants were sampled using pitfall traps positioned within rectangular vegetation transects (30 × 10 m). Both ant and plant species richness, when standardised for sampling effort, were unrelated to riparian corridor width. However, significant compositional differences between sites were evident with increased width up to ~50 m. Narrow corridors contained greater abundances of opportunistic ant species and higher proportions of exotic plants. We interpret this to be the result of the greater disturbance/edge influence derived from adjacent upland urban environments. Site beta diversity did not increase with corridor width, suggesting that the exclusion of novel upslope habitats in narrow riparian corridors is not a significant cause of community assemblage modification at these sites. To minimise the impact of deleterious edge effects on ant fauna, environmental managers should seek to retain riparian corridors wider than ~50 m. However, we observed substantial between-site variability of biotic assemblages, irrespective of corridor width. Therefore we recommend that environmental management practice needs to take a catchment-wide approach and consider other parameters that may contribute to riparian health so as to optimise the protection of riparian biodiversity.