Graphical representation of survival curves in the presence of time-dependent categorical covariates with application to liver transplantation

Graphical representation of survival curves is often used to illustrate associations between exposures and time-to-event outcomes. However, when exposures are time-dependent, calculation of survival probabilities is not straightforward. Our aim was to develop a method to estimate time-dependent survival probabilities and represent them graphically. Cox models with time-dependent indicators to represent state changes were fitted, and survival probabilities were plotted using pre-specified times of state changes. Time-varying hazard ratios for the state change were also explored. The method was applied to data from the Adult-to-Adult Living Donor Liver Transplantation Cohort Study (A2ALL). Survival curves showing a ‘split’ at a pre-specified time t allow for the qualitative comparison of survival probabilities between patients with similar baseline covariates who do and do not experience a state change at time t. Time since state change interactions can be visually represented to reflect changing hazard ratios over time. A2ALL study results showed differences in survival probabilities among those who did not receive a transplant, received a living donor transplant, and received a deceased donor transplant. These graphical representations of survival curves with time-dependent indicators improve upon previous methods and allow for clinically meaningful interpretation.     

Poverty and educational achievement in the US: A less-biased estimate using PISA 2012 data

In the current paper, we employ the most recent Programme for International Student Assessment (PISA) data to calculate a less-biased estimate of poverty on US achievement. The PISA was specifically chosen as it is an assessment removed from a specific curriculum and instead focuses on concepts that students should know in order to participate in a global economy. Using a propensity score matching approach, our findings suggest that US students in poverty have notable educational attainment deficiencies compared to a matched group of students who are not in poverty. In other words, when we select two students who have a great deal in common but for the fact that one comes from a poverty background, the student in poverty is expected to perform nearly 28 points, or about a quarter of a standard deviation lower, on the PISA assessment. In real terms, this puts math achievement for children not in poverty on-par with the Organisation for Economic Co-operation and Development (OECD) average, while children in poverty are well below the OECD average.     

The complexities of cultural support planning for Indigenous children in and leaving out‐of‐home care: the views of service providers in Victoria,Australia

Indigenous children and young people are over‐represented at all stages of the Australian child protection system. Policy and legislative initiatives exist in the state of Victoria, Australia aiming to support the connection between Indigenous children and young people in state care and their culture and community. This exploratory research involved focus group consultations with seven child and family welfare agencies to investigate the impacts, barriers, benefits and limitations of cultural support planning for Indigenous young people in, and leaving care in, Victoria. Findings indicated that cultural planning was of value when it could be completed. However, various shortcomings of current systems were identified including limited resourcing of Aboriginal Community Controlled Organisations to generate plans and provide direct and secondary consultation services to implement plans, difficulty gathering information for plans and some Indigenous young people expressing disinterest in connecting to their culture and community. Complexities in the relationships between the Indigenous and non‐Indigenous agencies that aimed to support Indigenous young people in care were also acknowledged. Participants identified a number of strategies to improve outcomes, such as facilitating better relationships between agencies, promoting opportunities for ongoing cultural training for staff in mainstream agencies and improving the resourcing of Aboriginal Community Controlled Organisations to deliver planning and to support cultural connections.     

Computationally and statistically efficient model fitting techniques

A significant challenge in fitting metamodels of large-scale simulations with sufficient accuracy is in the computational time required for rigorous statistical validation. This paper addresses the statistical computation issues associated with the Bootstrap and modified PRESS statistic, which yield key metrics for error measurements in metamodelling validation. Experimentation is performed on different programming languages, namely, MATLAB, R, and Python, and implemented on different computing architectures including traditional multicore personal computers and high-power clusters with parallel computing capabilities. This study yields insight into the effect that programming languages and computing architecture have on the computational time for simulation metamodel validation. The experimentation is performed across two scenarios with varying complexity.     

Planners’ Perceptions of Why Canadian Communities Have Too Many Plans

A survey of Canadian planners explored perceptions about factors contributing to the growing number of plans communities have adopted recently. The results suggest that practitioners see themselves as responding to current community concerns, as well as to requirements imposed by higher levels of government. Neoliberal practices that force compliance with accountability frameworks to enable transfer payments increase demands for new plans. Professional practices within planning have encouraged specialization—in fields such as urban design—that often leads to plan-making activities. With many plans to coordinate, and limited staff resources and time available, practitioners face increasing implementation challenges.     

Managers in the Global Economy: A Multilevel Analysis

We examine individual‐ and country‐level determinants of managerial employment, using data from the 1989 to 2009 waves of the World Values and European Values Surveys (n = 89,336 employed adults in 59 countries). Reflecting the rise of the transnational capitalist class, we find that factors related to globalization and international political institutions are most strongly associated with opportunities to join the managerial class relative to factors related to the business‐cycle or development. Additionally, in a subset of countries with detailed occupational information, we find that global trade has a particularly strong, positive association with the odds of being a corporate manager in a large firm.     

Impression Management,Super PACs and the 2012 Republican Primary

Super Political Action Committees (PACs) are new organizations within American politics allowing for unlimited donations to candidate campaigns. Super PACs helped make the 2012 Republican primary the most well‐funded primary in American history. Both candidates and Super PACs spend much of their money on televised campaign ads. My study of the 2012 Republican primary expands existing literature concerning political impression management by examining advertising imagery in the era of Super PACs. I developed a typology of performance types from a qualitative content analysis of television advertisements for both candidates and Super PACs. The significance of Super PACs as they interact and overlap with the images of candidate ads calls for analysis of the changing front stage in the political realm.