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.     

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.     

Cognitive and interpersonal abilities related to the primary activities of R&D managers

This study attempted to identify the primary activities performed by R&D managers at different supervisory levels, and the cognitive and interpersonal ability requirements that underlie these activities. A task inventory containing 244 managerial tasks was completed by 117 R&D managers in nine organizations. The 48 tasks which managers rated as having spent the most time were factor analyzed, resulting in the identification of three primary activities: project management, personnel supervision, and strategic planning. Furthermore, these activities varied with supervisory level, with R&D managers performing a wider range of these activities with the progression from first-line to upper-level management.Thirty R&D managers later rated the degree to which 19 cognitive and interpersonal abilities were required for performing these primary activities. Strategic planning was rated as requiring significantly higher levels of oral expression, logical reasoning, originality, fluency of ideas, oral defense, and resistance to premature judgement than was required for the other two primary activities. Personnel supervision required a higher level of social sensitivity than was required for the other two activities. Project management required high levels of information ordering, oral fact- finding ability, problem sensitivity, and oral and written comprehension. Implications of the findings for understanding R&D managerial performance and personnel staffing functions are discussed.     

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.     

Effective boards: how executive directors define and develop them

There is growing recognition in the nonprofit field that the executive director has a key role in determining whether the board of directors will function effectively. To aid executives in this vital role, two recent studies defined a "good board" from the point of view of two samples of executive directors of community agencies, then sought factors related to board performance as measured by this definition. In interviews, executives whose boards scored higher than their peers on this performance measurement related how they work with their boards in such areas as recruitment of new members, financial management, fundraising, and leadership development.     

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.     

Negotiating Tensions between Methodology and Procedural Ethics

In this commentary, I consider what can go wrong in research when tensions arise between methodology and procedural ethics. I recount difficulties negotiating and implementing a participant recruitment strategy during my doctoral research project, which aimed to explore the experiences of people affected by dementia in the United Kingdom who were disengaged from services. To access this hard-to-reach population, I intended to adopt an informal recruitment strategy, snowball sampling from personal contacts and striking up conversations in public places. The procedural ethics committee were unhappy with this approach, deeming it potentially coercive. They suggested a more formal recruitment strategy enacted via emailing community organisations and churches. This approach entailed practical consequences that ultimately weakened the study sample, data and findings. This case raises questions about the negotiation of tensions between methodology and procedural ethics in gerontological research.