Inference Methods for Correlated Left Truncated Lifetimes: Parent and Offspring Relations in an Adoption Study

The associations in mortality of adult adoptees and their biological or adoptive parents have been studied in order to separate genetic and environmental influences. The 1003 Danish adoptees born 1924–26 have previously been analysed in a Cox regression model, using dichotomised versions of the parents’ lifetimes as covariates. This model will be referred to as the conditional Cox model, as it analyses lifetimes of adoptees conditional on parental lifetimes. Shared frailty models may be more satisfactory by using the entire observed lifetime of the parents. In a simulation study, sample size, distribution of lifetimes, truncation- and censoring patterns were chosen to illustrate aspects of the adoption dataset, and were generated from the conditional Cox model or a shared frailty model with gamma distributed frailties. First, efficiency was compared in the conditional Cox model and a shared frailty model, based on the conditional approach. For data with type 1 censoring the models showed no differences, whereas in data with random or no censoring, the models had different power in favour of the one from which data were generated. Secondly, estimation in the shared frailty model by a conditional approach or a two-stage copula approach was compared. Both approaches worked well, with no sign of dependence upon the truncation pattern, but some sign of bias depending on the censoring. For frailty parameters close to zero, we found bias when the estimation procedure used did not allow negative estimates. Based on this evaluation, we prefer to use frailty models allowing for negative frailty parameter estimates. The conclusions from earlier analyses of the adoption study were confirmed, though without greater precision than using the conditional Cox model. Analyses of associations between parental lifetimes are also presented.     

Secular Trends in Alcohol Drinking Among Danish 15‐Year‐Olds: Comparable Representative Samples From 1988 to 2010

This study describes the secular trends in weekly intake of beer, wine, liquor, and drunkenness among 15‐year‐olds 1988–2010 (total N = 8,701), a period with several policy initiatives regarding alcohol in Denmark. Data from seven comparative and representative school surveys conducted in 1988, 1991, 1994, 1998, 2002, 2006, and 2010 were used. The proportion of 15‐year‐olds in Denmark who drank alcohol and were drunk increased from 1988 to 2002, but decreased substantially to 2010; for example, the proportion of 15‐year‐old girls who drank beer at least weekly increased from 15% in 1988 to 31% in 2002 and decreased to 7% in 2010. We hypothesize that age limits for purchasing alcohol may have resulted in a decrease in young people's alcohol use.     

Goodness of fit tests for estimating equations based on pseudo-observations

Lifetime Data Analysis - We study regression models for mean value parameters in survival analysis based on pseudo-observations. Such parameters include the survival probability and the cumulative...     

On the practical application of mixed effects models for repeated measures to clinical trial data

The use of mixed effects models for repeated measures (MMRM) for clinical trial analyses has recently gained broad support as a primary analysis methodology. Some questions of practical implementation detail remain, however. For example, whether and how to incorporate clinical trial data that is collected at nonprotocol‐specified timepoints or clinic visits has not been systematically studied. In this paper, we compare different methods for applying MMRM to trials wherein data is available at protocol‐specified timepoints, as well as nonprotocol‐specified timepoints due to patient early discontinuation. The methods under consideration included observed case MMRM, per protocol visits MMRM, interval last observation carried forward (LOCF) MMRM, and a hybrid of the per protocol visits and interval LOCF MMRM approaches. Simulation results reveal that the method that best controls the type I error rate is the per protocol visits method. This method is also associated with the least precision among the competing methods. Thus, in confirmatory clinical trials wherein control of type I error rates is critical, per protocol visits MMRM is recommended. However, in exploratory trials where strict type I error control is not as critical, one may prefer interval LOCF MMRM due to its increased precision. Points to consider with respect to both study design (e.g., assigning schedule of events) and subsequent analysis are offered. Copyright © 2012 John Wiley & Sons, Ltd.     

Young people looking forward: Imagined future and normative tensions in urban Norway

We explore the meaning-making practices of ‘little personal stories’ and ‘big societal stories’ in the imagined futures of 12- and 13-year-olds within Norway, known for its egalitarian ideals and welfare society. Using the concept ‘prospective narratives’, we explore these practices through the students' narrative world-making. The narratives connect the imagined future with gender and class variations related to larger social norms in the arenas of work and family. They demonstrate embodied and positioned cultural knowledge of the present, reflecting tensions between dominant social norms—‘big stories’—in terms of child-centred parenting, active work-life and egalitarian ideals across gender and class.     

People around you – do they matter? An experimental gambling study

The presence of others is assumed to intensify gambling behaviour. However, empirical findings are mixed. Against this backdrop, a gambling simulation experiment was designed, comprising three conditions (gambling alone, gambling with two unfamiliar others and gambling with two familiar others). A total of 136 participants were recruited and assigned to one of the conditions. Win-sequence (‘early’, ‘middle’ and ‘late’) was a sub-condition. The gambling simulation was based on the electronic gaming machine (EGM). The dependent repeated measures were ‘Total trials gambled’, ‘Bet size’, ‘Reaction time’ and ‘Credit’. Several univariate mixed regression models were fitted. Contrary to expectations, participants gambling alone gambled on average more trials, placed their bets faster and lost fewer credits over time compared to those gambling with other participants. Participants receiving reinforcements mainly during the first part of the session showed more persistence within the gambling session in comparison with participants receiving winnings mainly at a later stage of the session. This suggests that the arousal induced by fellow participants facilitated a standard of maximizing actual returns, resulting in a loss-avoidance strategy. As attitudes toward gambling in Norway are relatively negative, the results could also reflect normative group pressure or fear of negative evaluation from others.     

Durable consumption,saving and retirement

Durables yield services through life but are also a store of value and both features may have important implications for savings and retirement decisions. Durables also affect bequests and thus induce intergenerational transfers. We show that allowing explicitly for durables has important implications for retirement decisions and responses to various changes in the environment. An improvement in the possibility of freeing housing capital makes the old retire earlier (income effect) while the young plan to retire later since they increase housing demand and reduce financial savings. Considering welfare in stationary equilibrium, we find that a reduction in wealth locking-in in durables is not necessarily welfare improving due to the effects on bequests. From a social welfare perspective, individuals tend to choose too much financial savings, too little durable acquisition and too early retirement.     

Appearance-Related Communication and Body Image Outcomes: Fat Talk and Old Talk Among Mothers and Daughters

The current study sought to investigate mothers’ and daughters’ appearance-related communication and its relation to body image outcomes. Participants included 199 mother-daughter dyads that completed online questionnaires containing measures of fat talk, old talk, body dissatisfaction, body surveillance, drive for thinness, and bulimic tendencies. Actor-partner interdependence models revealed that (a) mothers’ and daughters’ fat talk, but not old talk, were significantly related to one another, (b) mothers’ and daughters’ fat talk and old talk were significantly related to their own body image outcomes, (c) mothers’ fat talk was positively related to daughters’ bulimic tendencies, and (d) mothers’ old talk was positively related to daughters’ body dissatisfaction. These results suggest that engaging in appearance-related communication is problematic for the person making the comments and, to some extent, being exposed to another person’s appearance-related comments can be harmful to the individual as well—at least for the daughters in the current sample.     

Assortative Mating and the Intergenerational Transmission of Parental Incarceration Risks

Research on the intergenerational transmission of incarceration tends to emphasize the strong association between fathers' involvement with the criminal justice system and sons' behavioral outcomes, such as experiencing incarceration. The father–son association in incarceration risks is, however, not the only mechanism through which these risks may travel across generations. Although female rates of incarceration are generally low (even for women who experienced parental incarceration when they were girls), women could transmit incarceration risks across generations through their choice of partner. This article uses administrative data on three generations in Denmark to show that assortative mating—the nonrandom selection of partners with similar characteristics—indeed make women just as likely as men to transmit incarceration risks across generations.