Introduction Instrumental variable (IV) analysis potentially accounts for unmeasured confounding in observational studies, but it can also control for noncompliance in randomized trials. IV analysis requires that the IV is related to treatment status, yet independent of confounders of the treatment-outcome relation. This implies that in pharmacoepidemiologic scenarios where IV analysis is neede...

Stochastic search variable selection (SSVS) algorithms provide an appealing and widely used approach for searching for good subsets of predictors while simultaneously estimating posterior model probabilities and model-averaged predictive distributions. This article proposes a two-level generalization of SSVS to account for missing predictors while accommodating uncertainty in the relationships ...

We examined the relationship between training regimen and fluid intelligence in the learning of a complex video game. Fifty non-game-playing young adults were trained on a game called Space Fortress for 30 hours with one of two training regimens: (1) Hybrid Variable-Priority Training (HVT), with part-task training and a focus on improving specific skills and managing task priorities, and (2) Fu...

Many experiments report that animals will work (lever press) for food in the presence of freely available identical food. This phenomenon has attracted the attention of applied ethologists because it seems to prove that animals have a need to express appetitive behavior. If this is the case, then it has implications for the provision of environmental enrichment for animals in captivity. In this...

Observational epidemiological studies suffer from many potential biases, from confounding and from reverse causation, and this limits their ability to robustly identify causal associations. Several high-profile situations exist in which randomized controlled trials of precisely the same intervention that has been examined in observational studies have produced markedly different findings. In ot...

Instrumental variable (IV) methods are becoming increasingly popular as they seem to offer the only viable way to overcome the problem of unobserved confounding in observational studies. However, some attention has to be paid to the details, as not all such methods target the same causal parameters and some rely on more restrictive parametric assumptions than others. We therefore discuss and co...

BACKGROUND The recent push for the publication of individual surgeon outcomes underpins public interest in safer surgery. Conventional, retrospective assessment of surgical performance without continuous monitoring may lead to delays in identifying poor performance or recognition of practices that lead to be better than expected performance. DISCUSSION The variable life adjusted display (VLAD...

where T0 is the so-called baseline life time and T is the observable life time. We will assume that T is an absolute continuous random variable (r.v.) and that the covariate X does not depend on the time. For simplicity of presentation let X be one-dimensional. For statistical application a suitable choice of the acceleration function is important and the problem of testing ψ arises. A survey o...

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