Marginal and hazard ratio specific random data generation: Applications to semi-parametric bootstrapping

Cox's partial likelihood for censored time-to-event data can be interpreted as a permutation probability, whereby covariate values are permuted to the observed times-to-event and censoring times. This interpretation facilitates a simple method for jointly generating times-to-event and covariate tuples with considerable flexibility, including time dependence of the hazard ratio and specification of both the marginal time-to-event and covariate distributions. This interpretation also facilitates a method for semi-parametric bootstrapping of hazard ratio estimators.     

Multidimensional Quality of Life: A New Measure of Quality of Life in Adults

This paper presents a new measure for assessing quality of life (QOL) –the Multidimensional Quality of Life (MQOL)– and describes its derivation, characteristics, structure and several applications. Reasons for developing the MQOL include the restricted range of assessed domains and the heavy emphasis on health in many standard assessment tools. The MQOL was derived by meaning probes into QOL in different samples. It is a 60-item self-report tool of high reliability and validity covering various themes and forming, in line with factor and cluster analyses, 17 scales that constitute five factors according to confirmatory factor analysis. It has been applied with thousands of individuals, in English, Hebrew, Russian and Arabic, and is adequate for healthy and physically or mentally sick individuals, under regular or challenging circumstances. Described studies present findings in samples of sick or healthy individuals (e.g., unemployed, members of a collapsing Kibbutz); relations between the MQOL and coping strategies in partners of sick individuals; and interrelations of overall and scale scores in new and old immigrants. Conclusions focus on the structure of the MQOL, the specificity of coping effects, and the stabilizing mechanisms of QOL.     

Using categorical markers as auxiliary variables in log‐rank tests and hazard ratio estimation

Markers, which are prognostic longitudinal variables, can be used to replace some of the information lost due to right censoring. They may also be used to remove or reduce bias due to informative censoring. In this paper, the authors propose novel methods for using markers to increase the efficiency of log‐rank tests and hazard ratio estimation, as well as parametric estimation. They propose a «plug‐in» methodology that consists of writing the test statistic or estimate of interest as a functional of Kaplan–Meier estimators. The latter are then replaced by an efficient estimator of the survival curve that incorporates information from markers. Using simulations, the authors show that the resulting estimators and tests can be up to 30% more efficient than the usual procedures, provided that the marker is highly prognostic and that the frequency of censoring is high.     

Saving Performance in Individual Development Accounts: Does Marital Status Matter?

Research indicates that marriage has a large effect on reducing the risk of poverty and is associated with a higher probability of attaining affluence over the life course when compared with nonmarriage. Using data from the American Dream Demonstration (N =2,364), this study compares savings performances of married and unmarried low‐income participants in a matched savings program—Individual Development Accounts. The results indicate that both married and unmarried low‐income participants can save in Individual Development Accounts. After controlling for program and other participant characteristics, there were no significant differences in savings between married and unmarried participants. We further examined possible factors that are associated with Individual Development Account savings performance for these two groups.     

Tree-structured subgroup analysis for censored survival data: Validation of computationally inexpensive model selection criteria

The performance of computationally inexpensive model selection criteria in the context of tree-structured subgroup analysis is investigated. It is shown through simulation that no single model selection criterion exhibits a uniformly superior performance over a wide range of scenarios. Therefore, a two-stage approach for model selection is proposed and shown to perform satisfactorily. Applied example of subgroup analysis is presented. Problems associated with tree-structured subgroup analysis are discussed and practical solutions are suggested.     

First-time mothers’ birth beliefs,preferences, and actual birth: A longitudinal observational study

Problem

Birth preferences, such as mode and place of birth and other birth options, have important individual and societal implications, yet few studies have investigated the mechanism which predicts a wide range of childbirth options simultaneously.

MARITAL QUALITY AMONG COUPLES LIVING UNDER THE THREAT OF FORCED RELOCATION: THE CASE OF FAMILIES IN THE GOLAN HEIGHTS

This study aims to explore how the long period of uncertainty about possible relocation affects the marital quality of the population in the Golan Heights and what forms of coping with this ongoing stress are used. The results, based on both quantitative and qualitative data, indicate a circular process in which the level of stress generated by the uncertainty varies with marital quality and with other personal and family resources, such as potency and an appreciation of the spouse's ability to cope with the stress. Four ways of coping with the uncertainty were observed in in-depth interviews: fighting, ignoring, postponing, and planning. The results are discussed in terms of their meaning for possible systemic interventions.     

Combined survival analysis of cardiac patients by a Cox PH model and a Markov chain

The control and treatment of dyslipidemia is a major public health challenge, particularly for patients with coronary heart diseases. In this paper we propose a framework for survival analysis of patients who had a major cardiac event, focusing on assessment of the effect of changing LDL-cholesterol level and statins consumption on survival. This framework includes a Cox PH model and a Markov chain, and combines their results into reinforced conclusions regarding the factors that affect survival time. We prospectively studied 2,277 cardiac patients, and the results show high congruence between the Markov model and the PH model; both evidence that diabetes, history of stroke, peripheral vascular disease and smoking significantly increase hazard rate and reduce survival time. On the other hand, statin consumption is correlated with a lower hazard rate and longer survival time in both models. The role of such a framework in understanding the therapeutic behavior of patients and implementing effective secondary and primary prevention of heart diseases is discussed here.     

(Un)available upon request: field experiment on researchers' willingness to share supplementary materials

This article reports results of a field experiment in which two hundred e-mails were sent to authors of recent articles in economics that had promised to send the interested reader supplementary material, such as alternative econometric specifications, "upon request." The e-mails were sent either by a researcher affiliated at Columbia University, New York or the University of Warsaw, Poland; furthermore, the authors' position (assistant professor) was specified in half the e-mails only. Overall, 64% of the approached authors responded to our message, of which two thirds (44% of the entire sample) delivered the requested materials. The frequency and speed of responding and delivering were very weakly affected by the position and affiliation of the sender. Gender or affiliation of the author, number of citations or journal impact factor or the type of object in question seemed to make no difference. However, authors of published articles were much more likely to share than authors of working papers.     

Individual and Familial Determinants of Married Arab Israeli Women's Labor Force Participation: Trends of Change and Stability

Although the Arab population in Israel has undergone important economic and social changes in the past decades, the labor force participation of Arab women, particularly married women, has remained limited. This study uses census data to learn about the individual and familial factors associated with the entry into paid work of married Arab women and examines the extent to which these factors have changed over time. A major advantage is that the study distinguishes between the Muslim, Christian, and Druze populations, who markedly differ in their demographic, social, and cultural characteristics. Results from logistic regression models and standardization analyses reveal that the growth in employment experienced by Arab women was associated with the increasing education of both wives and husbands. However, the returns to education significantly decreased over time, particularly among Druze women, suggesting it has become more difficult for highly educated women to find employment. Results further show that the growth in employment experienced by Muslim and Christian women was related both to a decline in fertility and to a decrease in the negative returns to having children. Overall, findings underscore the structural barriers that limit Arab Israeli women's employment opportunities and raise concerns about their future occupational prospects.