Joint modelling of multivariate longitudinal profiles: pitfalls of the random-effects approach

Due to its flexibility, the random-effects approach for the joint modelling of multivariate longitudinal profiles received a lot of attention in recent publications. In this approach different mixed models are joined by specifying a common distribution for their random-effects. Parameter estimates of this common distribution can then be used to evaluate the relation between the different responses. Using bivariate longitudinal measurements on pure-tone hearing thresholds, it will be shown that such a random-effects approach can yield misleading results for evaluating this relationship.     

Promises and pitfalls of meta-analysis in vaccine research

Meta-analysis continues to grow in usage despite increased concern regarding its soundness. Over twenty meta-analyses directly pertain to vaccines. Vaccine researchers need to understand the technique as well as the criticisms. Meta-analysis involves four steps. First, the meta-analyst should establish certain criteria in advance of the second step where the meta-analyst gathers the data--the results of the individual studies. Third, the meta-analyst assesses the individual studies for combinability and, fourth, the meta-analyst actually combines the data to generate conclusions. Vaccine meta-analyses have addressed a variety of vaccines and a variety of study objectives including efficacy, immunogenicity and safety. Three classical concerns revolve around the issue of publication bias, data dredging and individual study variability. Additionally, vaccine meta-analyses suffer concerns particular to the field of vaccine research.     

Experiencing change: progress and pitfalls

A small, rural community takes the effort to make the transition from a skilled nursing facility to an assisted living model of care delivery. These changes are needed because of the cost and access of services available in this setting. The system of care delivery being considered is based on the model called Aging in Place (AIP).     

Interpretations of smoking in film by older teenagers

Research testifies that images of tobacco use in popular films are highly pervasive and typically glamorised. There are concerns that these images may promote motivations to smoke in adolescents, but little is known about how these images are interpreted by members of this age group. A qualitative study was conducted to explore how older teenagers interpret and decode smoking imagery in film. This study builds on earlier work with a younger age group (12 and 13 years) to explore how various interpretations of smoking imagery shape and support common understandings about smoking among older teenagers.Data were collected through focus groups. Eighty-eight 16 and 17 year old students were interviewed at school. Participants discussed their recollections of and responses to recently viewed films. Older teens were receptive to smoking imagery when it was used in a credible manner to portray an emotional state, sub-culture affiliation, and lifestyle. Experience as a smoker appeared to inflate the credibility of realistic smoking images, particularly those presented in gritty realism/drama film. Older teens perceived realistic images, as opposed to stereotypical images, as a salient reference to their own lives. Stereotypical images were also readily recalled and appeared to perform an important role in supporting misconceptions about smoking and contributing to popular ideologies about tobacco use. Stereotypical images presented in comedy and action genre also serve to present paradoxical and contradictory messages about tobacco use. In particular, participants recalled tobacco use in film as associated with stress and anxiety, drug use, and seduction. Film images of tobacco use in specific contexts appear to hold specific and significant meanings for older teens. Realistic images offered salient representations of the perceived reality of smoking for this group. Pervasive and credible smoking scenes in film may offer support and reassurance to older teens who currently smoke or hold ambivalent views about smoking. Consistent with younger adolescents, older teens presented a predominantly nonchalant response to smoking imagery in film, which is a powerful indicator of the pervasiveness and acceptability of smoking in general. In contrast with younger adolescent, older teens tend to draw upon their own experience with tobacco use when interpreting smoking images in film.