Reducing sample size needed for cox-proportional hazards model analysis using more efficient sampling method

Abstract

In general, survival data are time-to-event data, such as time to death, time to appearance of a tumor, or time to recurrence of a disease. Models for survival data have frequently been based on the proportional hazards model, proposed by Cox. The Cox model has intensive application in the field of social, medical, behavioral and public health sciences. In this paper we propose a more efficient sampling method of recruiting subjects for survival analysis. We propose using a Moving Extreme Ranked Set Sampling (MERSS) scheme with ranking based on an easy-to-evaluate baseline auxiliary variable known to be associated with survival time. This paper demonstrates that this approach provides a more powerful testing procedure as well as a more efficient estimate of hazard ratio than that based on simple random sampling (SRS). Theoretical derivation and simulation studies are provided. The Iowa 65+ Rural study data are used to illustrate the methods developed in this paper.     

The intergenerational education spillovers of pension reform in China

Economic theory establishes that pension privatization weakens the link between old and young and so reduces the incentive to invest in public education in an economy with lower return rate of capital than growth rate of wage. However, empirical studies of the link change are few. In this paper, we investigate the effects of pension privatization and the central government’s subsidy to individual accounts on public education spending in a three-period overlapping generation model. And then, we take contemporary pension reforms in a number of Chinese provinces as offering natural experiment conditions. Using a difference-in-difference framework and 282 municipal districts panel data over years 1998–2009, we test the pension-education theoretical link change. Both our theoretical and empirical results confirm that pension privatization is adversely associated with local public spending on education in China. Private pension subsidies, moreover, magnify this effect. Our study supports the theoretical assertion and selective empirical findings of a negative intergenerational effect of pension privatization.     

A majorization comparison of apportionment methods in proportional representation

From the inception of the proportional representation movement it has been an issue whether larger parties are favored at the expense of smaller parties in one apportionment of seats as compared to another apportionment. A number of methods have been proposed and are used in countries with a proportional representation system. These apportionment methods exhibit a regularity of order, as discussed in the present paper, that captures the preferential treatment of larger versus smaller parties. This order, namely majorization, permits the comparison of seat allocations in two apportionments. For divisor methods, we show that one method is majorized by another method if and only if their signpost ratios are increasing. This criterion is satisfied for the divisor methods with power-mean rounding, and for the divisor methods with stationary rounding. Majorization places the five traditional apportionment methods in the order as they are known to favor larger parties over smaller parties: Adams, Dean, Hill, Webster, and Jefferson. Received: 5 August 2000/Accepted: 24 October 2001     

Sex Related Factors in the Perception of Threatening Facial Expressions

This study replicated and extended previously reported sex differences involving both viewer and target in the recognition of threatening facial expressions. Based on the assumption that the evolved cognitive mechanisms mediating anger recognition would have been designed by natural selection to operate quickly in the interests of survival, brief tachistoscopic presentation of stimulus photographs was used. Additionally, in contrast to prior published studies, the statistical methods of signal detection research were used to control for the confounding effects of non-random guessing. The main hypothesis, that anger posed by males would be more accurately perceived than anger posed by females, was supported. A secondary hypothesis, that female-posed anger would be more accurately perceived by women than by men, received partial support. Testosterone levels, measured inferentially in terms of diurnal cycles, failed to show the hypothesized positive relationship to accuracy of anger perception.     

The PALS parenting support programme: lessons learned from the evaluation of processes and outcomes

Although there has recently been a rise in parenting support programmes within the UK, only a minority of these programmes have benefited from evaluation of either outcomes or processes. This paper describes the development of the PALS programme (Parents Altogether Lending Support), reporting both on its effectiveness in improving parents' interactions with their children and on the lessons that were learned about embedding such a programme within the local community. Over the 18‐month period of the programme, a total of 17 courses were run, with 75 parents and carers (primarily mothers) participating in the programme overall. Evaluation results indicated that participants enjoyed the course and found it beneficial, particularly in terms of altering their own actions in specific ways that were able to promote better behaviour on the part of their children. Participants also valued the opportunity to share their experiences with other parents. The key lesson identified in regard to the development of parenting programmes concerned the need for the community to feel a sense of ownership for the initiative. Copyright © 2002 John Wiley & Sons, Ltd.     

Book Review: Funding Virtue: Civil Society Aid and Democracy Promotion,Marina Ottaway and Thomas Carothers (eds.), Carnegie Endowment for International Peace,Washington, DC, 2000

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations -     

Existence and Nash implementation of efficient sharing rules for a commonly owned technology

Suppose that a group of individuals owns collectively a technology which produces a consumption good by means of a (possibly heterogeneous) input. A sharing rule associates input contributions with a vector of consumptions that are technologically feasible. We show that the set of allocations obtained by any continuous sharing rule contains Pareto efficient allocations. We also present a mechanism that implements in Nash equilibrium the Pareto efficient allocations contained in an arbitrary sharing rule. Received: 29 June 1998/Accepted: 15 November 2000     

REVIEWS

Bailey, C. E. (Ed.) (2000). Children in therapy: Using the family as a resource. Doherty, W. J. (2001). Take back your marriage: Sticking together in a world that pulls us apart. New York: Guilford. Larson, J. H. (2000). Should we stay together? A scientically proven method for evaluating your relationship and improving its chances for long‐term success. Weiner‐Davis, M. (2001). The divorce remedy: The proven 7‐step program for saving your marriage.     

Life Experiences and Vulnerabilities of Homeless Women: A Comparison of Women Unaccompanied Versus Accompanied by Minor Children, and Correlates with Children's Emotional Distress

The histories and service needs of 2 groups of homeless women, those unaccompanied by minor children (n = 46) and those accompanied by minor children (n = 22), were compared, on the basis of their responses to a biennial survey of homeless people in a midsize city in the southeast United States. Mothers of children aged 2–10 also completed a measure of stress symptoms for their children (n = 20). Irrespective of family status group, problems such as substance abuse, history of mental illness, health problems, chronicity of homelessness, and crime victimization tended to cluster together. The findings also suggest that declining and/or inadequate levels of public benefits, Temporary Assistance to Needy Families, and Medicaid-funded health care in particular, have adversely affected the 2 groups, particularly families with children. The young children in this sample experienced elevated levels of stress, and significant associations were found between children's stress levels and certain risk factors of their mothers. Implications for service delivery are discussed.