Reweighted estimators for additive hazard model with censoring indicators missing at random

Survival data with missing censoring indicators are frequently encountered in biomedical studies. In this paper, we consider statistical inference for this type of data under the additive hazard model. Reweighting methods based on simple and augmented inverse probability are proposed. The asymptotic properties of the proposed estimators are established. Furthermore, we provide a numerical technique for checking adequacy of the fitted model with missing censoring indicators. Our simulation results show that the proposed estimators outperform the simple and augmented inverse probability weighted estimators without reweighting. The proposed methods are illustrated by analyzing a dataset from a breast cancer study.     

Economic Conditions of Young Adults Before and After the Great Recession

Transition to adulthood has undoubtedly changed in the last few decades. For youth today, an important marker of adulthood is self-actualization in their professional career, and, consequently, also the achievement of stable financial conditions. Economic conditions of youth are greatly subject to fluctuations in the economy, and the subsequent governmental response. Using the Luxembourg Income Study, this work investigates the trends in income from work of young adults before and after the Great Recession of 2008 in five countries—US, UK, Norway, Germany, and Spain. The findings showed deterioration in economic conditions of young men, but with differences across countries. Young women suffered less from the crisis, and in some countries, their economic situation improved. The general negative trend was especially pronounced for those with high education, which is primarily because they stayed in education longer.     

Decomposing the increase in men’s time on childcare during the great recession

In this paper, I examine the time men spent on childcare during the recession of 2007–2009. The recession provides a sudden change in the employment opportunities of men relative to women in the United States. Using the American Time Use Survey and the linked Current Population Survey, I show that this lopsided shock to employment opportunities was accompanied by an increase in the average amount of time men spent on childcare. In particular, men’s average time on physical care for children increased during the recession; this is an element of childcare that men perform less than women. I decompose the total change in average time on childcare into behavioral, compositional, and between group change. A behavioral change among employed men accounted for the majority of the total increase in the average time spent on childcare; among men who are out of the labor force, the increase is entirely due to compositional changes.     

Social-ecological innovation: adaptive responses to urban environmental conditions

Novel approaches to natural resource management, particularly those which promote stakeholder participation, have been put forward as fundamental ingredients for establishing resilient, polycentric forms of environmental governance. This is nowhere more pertinent than in the case of the complex adaptive systems associated with urban areas. Decentralisation of urban green space management has been posited as an element thereof which, according to resilience thinking, should contribute to the adaptive capacity of cities and the ecosystem services upon which they rely. Implicit in this move towards increased adaptive capacity is the ability to manage through innovation. Although the importance of innovation towards system adaptability has been acknowledged, little work has thus far been carried out which demonstrates that innovative use of urban green space represents a form of adaptive response to environmental conditions. The current paper reports on research which maps examples of organised social-ecological innovation (OSEI) in an urban study area and evaluates them as adaptive responses to local environmental conditions which may contribute to system resilience. The results present OSEI as a coherent body of responses to local social and environmental deprivation, exhibiting diversity and adaptability according to individual contexts. The study therefore provides evidence for the importance of local stakeholder-led innovation as in the building of adaptive capacity in urban social-ecological systems.     

Multi-neighborhood based iterated tabu search for routing and wavelength assignment problem

The routing and wavelength assignment problem (RWA) has shown to be NP-hard if the wavelength continuity constraint and the objective of minimizing the number of wavelengths are considered. This paper introduces a multi-neighborhood based iterated tabu search algorithm (MN-ITS), which consists of three neighborhoods with a unified incremental evaluation method, to solve the min-RWA problem. The proposed MN-ITS algorithm is tested on a set of widely studied real world instances as well as a set of challenging random ones in the literature. Comparison with other reference algorithms shows that the MN-ITS algorithm is able to improve five best upper bounds obtained by other competitive reference algorithms in the literature. This paper also presents an analysis to show the significance of the unified incremental evaluation technique and the combination of multiple neighborhoods.     

Obesity and sex ratios in the U.S.

This paper studies how rising male incarceration and its impact on marriage markets has affected female incentives to gain weight. Exogenous variation in marriage market conditions is obtained from differential trends in male incarceration rates across markets defined by race, location and age. We provide evidence that marriage market conditions do in fact affect the incidence of obesity. In particular, we find that increases in male imprisonment that reduced the male–female sex-ratio explain about 18 % of the increase in the female obesity rate for African-Americans in the United States over the 1990s. Results are particularly large for those in the younger age group (ages 18–23).     

Conservative accounting as a signaling device in debt covenants

This paper provides a signaling explanation for benefits of conservative accounting in a debt contracting setting. It develops a model in which firms want to finance more or less risky projects through debt, which is private information. Creditors price the risk on average riskiness, which implies a relatively high interest rate for low-risk firms. These firms can signal their low-risk type by implementing a conservative accounting system. The accounting signal is used in a debt covenant that stipulates early repayment in case of a bad signal. Thus, the low-risk firms benefit from a lower interest cost, but at the cost of higher risk of being forced to liquidate a profitable project. The analysis establishes conditions for separating and pooling equilibria and determines their individual and social welfare implications. It shows that conservative accounting by low-risk firms can even increase social welfare if it mitigates underinvestment.     

Use It or Save It? Migration Background and Parental Leave Uptake in Sweden

Sweden is a welfare state with a family policy that strongly emphasizes equality without distinction by place of birth or gender. In this study, we investigate the differences in uptake of parental leave between native and immigrant mothers, and the connection to labour-market attachment. Sweden represents a unique case study, not only because of the strong effort to combine work and family for all women and men, the high level of fertility and the large presence of immigrants in the country; it also enables a detailed and sophisticated analysis based on the high-quality data derived from its population registers. We find that immigrant mothers use more parental leave benefit the first year after their child’s birth, but then fewer in the second year compared with native mothers. The differences diminish when labour-market activity is controlled for. Additionally, after a time in Sweden, immigrant mothers use leave more similarly to how native mothers do.     

Models of the Joint Structure of Domain-Related and Global Distress: Implications for the Reconciliation of Quality of Life and Mental Health Perspectives

Research on subjective wellbeing includes studies of both domain-related and global distress. The mental health literature, though, focuses almost exclusively on global distress. This seems to be partly due to a common belief that psychological distress, and the moods that comprise distress, necessarily lack referential content. However, if that were the case it would make little sense for any study to ever focus on domain-related distress. The research presented in this report clarifies the relation between global and domain-related distress. We compare confirmatory factor analytic models of the joint relationship among symptoms of global distress with affective symptoms of distress about work, home, and physical appearance. Data are from a general population telephone survey. In the best-fitting models domain-related distress and global psychological distress are related but distinct latent variables. We discuss the theoretical and methodological implications of the models, and model choice.