Non-ignorable missing covariate data in survival analysis: a case-study of an International Breast Cancer Study Group trial

Summary.  Non-ignorable missing data, a serious problem in both clinical trials and observational studies, can lead to biased inferences. Quality-of-life measures have become increasingly popular in clinical trials. However, these measures are often incompletely observed, and investigators may suspect that missing quality-of-life data are likely to be non-ignorable. Although several recent references have addressed missing covariates in survival analysis, they all required the assumption that missingness is at random or that all covariates are discrete. We present a method for estimating the parameters in the Cox proportional hazards model when missing covariates may be non-ignorable and continuous or discrete. Our method is useful in reducing the bias and improving efficiency in the presence of missing data. The methodology clearly specifies assumptions about the missing data mechanism and, through sensitivity analysis, helps investigators to understand the potential effect of missing data on study results.     

Assimilation as multiracialism: The case of Singapore's Malays

The myths of meritocracy and multiracialism ‘explain’ between them both the ‘fairness’ of the Singapore system and the subordinate role of the non-Chinese minority races. They also purport to assure the minorities that they enjoy full status as members of the nation-building project and that their cultural and religious mores are embraced and protected within its framework. Using the Malay minority as its case study, and arguing from archival, oral, official government and secondary sources, this paper argues that the Singapore systems of meritocracy and multiracialism have not been concerned primarily with intercommunal tolerance since the 1970s, but are now programmes of assimilation of the racial minorities into a Chinese-dominated society.     

Statistics for weighing benefits and harms in a proposed genetic substudy of a randomized cancer prevention trial

Summary.  When evaluating potential interventions for cancer prevention, it is necessary to compare benefits and harms. With new study designs, new statistical approaches may be needed to facilitate this comparison. A case in point arose in a proposed genetic substudy of a randomized trial of tamoxifen versus placebo in asymptomatic women who were at high risk for breast cancer. Although the randomized trial showed that tamoxifen substantially reduced the risk of breast cancer, the harms from tamoxifen were serious and some were life threaten-ing. In hopes of finding a subset of women with inherited risk genes who derive greater bene-fits from tamoxifen, we proposed a nested case–control study to test some trial subjects for various genes and new statistical methods to extrapolate benefits and harms to the general population. An important design question is whether or not the study should target common low penetrance genes. Our calculations show that useful results are only likely with rare high penetrance genes.     

Real nonparametric regression using complex wavelets

Summary.  Wavelet shrinkage is an effective nonparametric regression technique, especially when the underlying curve has irregular features such as spikes or discontinuities. The basic idea is simple: take the discrete wavelet transform of data consisting of a signal corrupted by noise; shrink or remove the wavelet coefficients to remove the noise; then invert the discrete wavelet transform to form an estimate of the true underlying curve. Various researchers have proposed increasingly sophisticated methods of doing this by using real-valued wavelets. Complex-valued wavelets exist but are rarely used. We propose two new complex-valued wavelet shrinkage techniques: one based on multiwavelet style shrinkage and the other using Bayesian methods. Extensive simulations show that our methods almost always give significantly more accurate estimates than methods based on real-valued wavelets. Further, our multiwavelet style shrinkage method is both simpler and dramatically faster than its competitors. To understand the excellent performance of this method we present a new risk bound on its hard thresholded coefficients.     

Struggles with Time: the careers of parents with adult sons and daughters with learning disabilities

The experiences of parents with adult offspring with learning disability and the meanings their parental careers have for them, has been the subject of very little empirical research. In this paper we describe and examine some of the features that gave shape and meaning to the day to day lives of parents of 33 co-resident adults with learning disabilities. Their accounts of their situations revealed that 'time' was a factor of some importance. Participants suggested that socialisation into the parental role was one that continued over the life course. In addition, they also felt that the services they received were based upon an inadequate and too narrow an understanding of how they experienced 'time'. The data reveal that both 'over time' and 'in time', parents struggled to maintain a set of aspirations for a typical life. The data show that for many parents there was a slow accommodation to the constraints of service provision and, as a result, their needs for service support became less extensive.     

Unjust Freedom: The Ethics of Client Self-Determination in Runaway Youth Shelters

Client self-determination has been called the most confounding and professionally debilitating concept of all the intellectual principles under-girding social work (Rothman, 1989). Identifying the appropriate parameters of client self-determination is a particularly acute problem for social workers employed by runaway and homeless youth shelters where minors are making adult decisions free from parental guidance. We examine the ethical dimensions of practice with minor clients in runaway shelters by arguing that a conflict exists between the liberty-based principle of self-determination and the justice-based notion of client competency. We analyze the conflict by using minimal distributive justice as the organizing principle of social work practice. We conclude that client self-determination in runaway shelters should be restricted and that presuming client competence violates the basic value tenets of the profession.     

Associations Between Observed Mother–Adolescent Interactions and Adolescent Information Management

Associations between observed mother–adolescent interactions during a conflict task and adolescents’ information management strategies were examined in 108 primarily middle class, European‐American adolescents (M = 13.80 years, SD = 1.52) and their mothers. Teens who communicated more clearly disclosed more about personal and multifaceted activities, lied less about personal activities, and engaged in less avoidance regarding multifaceted and prudential activities. Mothers’ clear communication was associated with less adolescent disclosure and more avoidance about personal and multifaceted activities. Teens with more receptive mothers omitted less prudential information but avoided discussing prudential issues more. Maternal warmth was not associated with information management. The results highlight the need to distinguish between parent and teen behaviors and between affective quality and specific communicative behaviors.     

A grounded theory of living a life with a physical disability in Taiwan

This study explores the experiences of disability for a number of Taiwanese adults with a physical disability. Using a grounded theory approach, their experiences of living a life with a physical disability were gained through in-depth interviews. The resulting grounded theory ‘it is more than just the impaired body’ presents the dynamic interactions between the participants and the context in which they were living their lives and how they managed their lives within that context. With its inclusion of the cultural dimension, a holistic way of understanding the daily lives of those who experience physical disability in Taiwan is provided.