Sample size calculations for clinical studies allowing for uncertainty about the variance

One of the most important steps in the design of a pharmaceutical clinical trial is the estimation of the sample size. For a superiority trial the sample size formula (to achieve a stated power) would be based on a given clinically meaningful difference and a value for the population variance. The formula is typically used as though this population variance is known whereas in reality it is unknown and is replaced by an estimate with its associated uncertainty. The variance estimate would be derived from an earlier similarly designed study (or an overall estimate from several previous studies) and its precision would depend on its degrees of freedom. This paper provides a solution for the calculation of sample sizes that allows for the imprecision in the estimate of the sample variance and shows how traditional formulae give sample sizes that are too small since they do not allow for this uncertainty with the deficiency being more acute with fewer degrees of freedom. It is recommended that the methodology described in this paper should be used when the sample variance has less than 200 degrees of freedom.     

Power and sample size considerations in clinical trials with competing risk endpoints

In clinical trials with a time-to-event endpoint, subjects are often at risk for events other than the one of interest. When the occurrence of one type of event precludes observation of any later events or alters the probably of subsequent events, the situation is one of competing risks. During the planning stage of a clinical trial with competing risks, it is important to take all possible events into account. This paper gives expressions for the power and sample size for competing risks based on a flexible parametric Weibull model. Nonuniform accrual to the study is considered and an allocation ratio other than one may be used. Results are also provided for the case where two or more of the competing risks are of primary interest.     

CONSTRUCTING A HEALTH AND SOCIAL INDICATOR FRAMEWORK FOR INDIGENOUS COMMUNITY HEALTH RESEARCH

Health and social indicators that capture the distinct historical, social, and cultural contexts of Indigenous communities can play an important role in informing the planning and delivery of community interventions. There is currently considerable interest in cataloguing and vetting meaningful community-level health and social indicators that could be applied to research and health promotion activities in Indigenous communities in Australia, Canada, and New Zealand, inclusive of conventional indicators as well as measures developed specifically for use in or with Indigenous communities. To avoid haphazard selection of indicators, and to assure the comprehensiveness and relevance of any given set of indicators, a framework that can accommodate and conceptually classify indicators representing a full range of domains is required. We report here on the development of a conceptual framework, by which Indigenous community indicators, and more general community-level social indicators, can be sorted, catalogued, and systematically classified within four hierarchical levels. The indicator framework was developed across Canada, Australia and New Zealand in consultation with academic researchers and Indigenous community stakeholders, building from established health and social indicator systems. The Indigenous indicator framework permits Indigenous communities, public health researchers, and funding agencies to compare and select the most appropriate indicators for application in specific contexts from the multitude of existing indicators.     

论体育游戏在体育教学中的三大价值

本文提示体育游戏的机理 ,证明这一机理在体育课中的价值 ,即内容手段价值、组织建构价值与模式指导价值 ,同时指出各价值的表现形式及所需条件     

Family and Nonfamily Role Configurations in Two British Cohorts

The aim of this paper is to examine variations in the combination of social roles during times of social change. We specify a latent class approach to examine role configurations for individuals in their early 30s, establishing a typology of how work‐ and family‐related roles combine within individuals born 12 years apart and examine their antecedents. Drawing on data collected for two British Birth Cohorts born in 1958 (N = 10,706) and 1970 (N = 11,005), we provide empirical evidence of both consistency and change in life course patterns. Findings are discussed in terms of destandardization, differentiation, and individualization of the life course in times of social change and their implications for family research within a life course perspective.     

Determinanten der Sportaktivität und der Sportart im Lebenslauf

This paper investigates the impact of social class, occupational and family life-course, relocation, age, generation and gender on exercise. Longitudinal, life course-oriented analysis enables identification of the (often diverse) conditions for (re-)uptake and discontinuation of exercise. The paper takes a detailed look at different types of exercise, enabling exploration of the various motivating influences and barriers involved. The database is a retrospective representative survey of the 50 to 70 year old population of Baden-Württemberg, Germany. The results show that higher educational qualifications are associated with higher levels of exercise, whereas manual labor and – among women – childcare are associated with lower levels of exercise. With respect to the impact of education, cultural rather than economic capital seems to be the determining influence. Other factors – (un-)employment, partnership, relocation, age and cohort – tend to have more complex effects on exercise. Though being a member of the workforce reduces the likelihood of starting to exercise, it also reduces the likelihood of dropping out. Though partnership encourages the dissemination of exercise, initiation of a relationship is also associated with a higher incidence of discontinuation. Relocation prompts both initiation and discontinuation of exercise. Surprisingly, up to the over-50 age group, increasing age is associated with an increased prevalence of physical activity, especially among women. The results of analysis of social differences in terms of types of physical activity can be used in health programs to provide scientifically founded recommendations for the promotion of specific types of physical activity for lower educational groups, seniors, and other social groups whose lifestyle tends to be inactive.     

Reconsidering identity: the ethnic and political dimensions of hybridity among majority and Turkish youth in Germany and England1

Sociological research has hitherto largely focused on majority ² and minority ethnic identities or citizenship identities. However, the social connections between youth are not simply ethnic dynamics but also political dynamics involving citizenship categories. This article argues that in postmodern societies, it is important to reconsider the ways we think about youth identities. Drawing upon qualitative data from a study into the political identities of majority (German and British) youth and Turkish youth, educated in two Stuttgart and two London secondary schools, the research found that fifteen‐year‐olds had no singular identity but hybrid ethno‐national, ethno‐local and national‐European identities as a result of governmental policies, their schooling and community experience, social class positioning, ethnicity and migration history. In working‐class educational contexts, many majority and Turkish youth privileged the ethnic dimension of hybridity whereas majority and Turkish youth in the two middle‐class dominated schools emphasized the political dimension of hybridity. The article demonstrates that social class and schooling (e.g. ethos and peer cultures) have a considerable role to play in who can afford to take on the more hybridized cosmopolitan identities on offer.     

教育生态学理论视角下的和谐生态课堂构建探究--以英语专业精读课堂为例

教育生态学理论为研究英语专业精读课堂教学模式的构建提供了一个全新的思路。本文从教育生态学视角出发,采用问卷调查、课堂观察和师生访谈对某高校外国语学院英语专业2年级精读课堂这一微观生态系统进行分析,得出以下结论：该校2年级精读课堂生态现状失衡。最后本文结合失衡的表现,提出了相应的措施,旨在提高精读课堂教学的有效性。     

The estimation of a corporate crisis communication

This experimental study found a main effect of perceived leadership and an interaction effect of perceived leadership and perceived severity of threats on the public's estimation of organizational crisis responses. The results indicate that the contingent theoretical argument explaining the dynamics of organizational factors and situational factors that determine stance taken by public relations practices can also be applied when explaining the outside latent public's thought patterns predicting an organizational stance and message strategy. Contingency theory offers predictive power, not just for the practitioner, but for the public passing judgment on the stance taken by an organization.     

‘I Can't Put a Smiley Face On’: Working‐Class Masculinity,Emotional Labour and Service Work in the ‘New Economy’

The growth of the ‘service economy’ has coincided with the large‐scale detachment from the labour market of low‐skilled men. Yet little research has explored exactly what it is about service work that is leading such men to drop out of the labour market during periods of sustained service sector employment growth. Based on interviews with 35 unemployed low‐skilled men, this article explores the men's attitudes to entry‐level service work and suggests that such work requires skills, dispositions and demeanours that are antithetical to the masculine working‐class habitus. This antipathy is manifest in a reluctance to engage in emotional labour and appear deferential in the service encounter and in the rejection of many forms of low‐skilled service work as a future source of employment.