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.     

Computer support of placement planning: the use of expert systems in child welfare

Computers have become commonplace in nearly every setting, from home to office. In addition to their usefulness for managerial tasks, they have the potential to aid the primary decision-making tasks of professional social service workers. The benefits and background of such "expert systems" are explored, and the structure of one experimental consulting program for child welfare workers, PLACECON, is presented.     

Public Multichannel Management – an Integrated Framework of Off- and Online Multichannel Government Services

Government institutions have introduced multichannel environments over time following trends and technological innovations. These public multichannel environments often neglect specific channel characteristics and potentials and thus miss the opportunity to make full use of a strategic channel integration and combination with a focus on customer value creation. This study offers a systematic approach to establish an integrated public multichannel system not only taking into account user preferences, habits and their environment, but also the respective channel issuer and the characteristics of channels and public interfaces. Against this background, the study presents a systematic approach to expand services and channels according to their capacities, and provides academics and practitioners with a framework on public multichannel strategies.     

Urban and peri-urban agriculture and its implication on food and nutrition insecurity in northern Ghana: a socio-spatial analysis along the urban–rural continuum

Food and nutrition insecurity remains a challenge in sub-Saharan Africa. Several studies have examined food and nutrition insecurity in urban or rural areas but have not captured the whole continuum. Between November and December 2013, 240 households were surveyed along the urban–rural continuum in Northern Ghana. The study objective was to understand the socio-spatial dynamics of household food and nutrition insecurity and to investigate the role played by urban, peri-urban and rural agriculture. The study found that there was more involvement in agriculture in rural areas compared to peri-urban areas and urban areas. Households from urban areas were more food insecure (HFIAS >?11) compared to their counterparts in peri-urban and the rural areas. Stunting increased by 3.4 times (p?=?0.048) among households located in the peri-urban area. Wasting was reduced by 0.16 times among household that produced staple food or vegetables (p?=?0.011). Overweight was reduced by 0.04 times among households that produced livestock (p?=?0.031). The results reveal a socio-spatial dimension of food and nutrition insecurity that is related to agricultural activities.     

Mental Illness and Criminal Behavior

The tragic events in Aurora, CO and Newtown, CT have renewed public perception of mentally persons as ‘dangerous’ and ‘criminal.’ Unfortunately, this perception is based more on conjecture and fear than research. The following essay takes stock of the empirical research on mental illness and criminal behavior. Three noteworthy trends emerge from this literature. First, the prevalence of mental illness is substantially higher among individuals who have come in contact with the criminal justice system relative to the general population. Second, individuals with psychotic and externalizing behavioral disorders, particularly those who also abuse drugs and alcohol, tend to engage in higher levels of violence than individuals with other forms of mental illness. Third, mental illness does not determine whether someone will break the law; rather, it is but one of many criminogenic risk factors that interact in complex ways to influence individual behavior.     

Reputation spillover effects from grant‐providing institutions

There is a broad academic discussion about the impact of funding grants from a foundation or a government department on individual support intentions toward the nonprofit organization receiving the grant. However, the role of the grant provider's reputation has frequently been overlooked. In this study, we experimentally tested whether there is a reputation spillover effect of a grant‐providing organization. Based on a real‐life example, we asked citizens to rate their willingness to donate to a nonprofit organization, and we experimentally manipulated the available information on funding sources. We test this for both a government department and a foundation as a grant provider. Our results suggest that not the act of receiving a grant, but the citizens' awareness about the funding organization—at least in the case of a foundation—has an impact on support intentions. In contrast, for a prominent government department as a grant provider, we did not find support for a reputation spillover effect.     

Estimating urban lawn cover in space and time: Case studies in three Swedish cities

Lawns are considered monocultures and lesser contributors to sustainability than diverse nature but are still a dominating green area feature and an important cultural phenomenon in cities. Lawns have esthetical values, provide playground, are potential habitat for species, contribute to carbon sequestration and water infiltration, but also increase pesticides, fertilization, are monocultures and costly to manage at the same time. To evaluate the potential impact of lawns, whether positive or negative, it is of interest to estimate the total lawn cover in cities and its change over time. This is not a straightforward process, e.g., because many lawns are small and covered by trees. In this study we review the existing literature of lawn cover in cities and the different methodologies used for cover estimation. We found both pros and cons with NDVI and LiDAR data as well as manually interpreted aerial photos. The total cover of lawns in three case study cities was estimated to 22.5%. By extrapolating these percentages to all Swedish cities lawn cover was estimated to 2589 km² (0.6% of the terrestrial surface). The approximated total municipal management cost of lawns in all Swedish cities was 910,000,000 USD/ year. During 50 years lawn area almost doubled in relative cover and 56% of them were continuously managed. Since lawns constitute large parts of the urban greenery and are costly to manage it is highly relevant to consider their social, ecological and cultural value compared to alternatives, e.g., meadows with less intensive management.     

Civil Society Organisations in Research: A Literature-Based Typology

This article explores literatures from various sources to highlight and understand differences among key players surrounding the perceived nature and role of civil society in research from different literature streams. Including Civil Society Organisations (CSOs) in research activities is an integral part of a broad drive towards integration of science and society. Interest in CSO inclusion in research is widespread, but lacks a coherent focus and clarity on what CSOs are. Without this clarity, CSO-inclusive research, or policy, may be ineffective. This article addresses this gap in knowledge by presenting findings from an exploration of academic, policy and research project literature in order to come to a view on CSOs in research. This culminates in a typology of CSOs and provides a means of identifying types of CSOs. The typology shows four main types of CSO (common cause, shared voice, research-oriented, commercially oriented) and provides a definition for each type, along with a basis for the definition; an example of each; some typical terminology; typical area of activity; properties; typical mission; key areas of interest and their ‘action logic’ in research.     

A note on interdependent happiness

Based on two models of interdependent utilities [Becker, G., 1974. A theory of social interaction, Journal of Political Economy 82, 1064–1093; Fehr, E., Schmidt, K., 1999. A theory of fairness, competition, and cooperation, Quarterly Journal of Economics 114, 817–868] we derive a functional relationship between average happiness and the standard deviation of happiness within a country. This hypothesis is supported by an empirical investigation of 71 countries which shows that the average happiness in these countries depends only on income and on the standard deviation of happiness σ. The latter may be partly based on influences beyond income, for which no data are available. Income has the expected positive influence and σ has the expected negative influence, i.e. large differences in “autonomous” happiness have a dampening influence on “effective” happiness which also takes into account the happiness of others.