According to the authors, time-modified confounding occurs when the causal relation between a time-fixed or time-varying confounder and the treatment or outcome changes over time. A key difference between previously described time-varying confounding and the proposed time-modified confounding is that, in the former, the values of the confounding variable change over time while, in the latter, t...

where u ∼ N(0, G) and 2 ∼ N(0, R) with u and 2 independent. This model can be interpreted as Y |β, u ∼ N(Xβ+Zu,R), u ∼ N(0, G), yielding (on integrating out u) the marginal model Y |β ∼ N(Xβ,ZGZ + R). Let V = ZGZ + R. Then the maximum penalized likelihood estimates of β and u given G and R are given by θ̂ = [ β̂ û ] = (CTR−1C + B)−1CTR−1y (A.2) where C = [X Z] and B is the block diagonal matrix w...

Longitudinal studies, where data are repeatedly collected on one subject over a period, are common in medical research. When effect of a time-varying exposure on an outcome of interest is measured at different time points, standard statistical methods fail to give robust estimate in the presence of time-dependent confounders. There is alternative method avoid, that is, inverse probability weigh...

A concept known as ‘marginal gains’, an approach to performance improvement in elite sport came to prominence during the London 2012 Olympics when Team GB cycling won a record eight gold medals. Since National Lottery funding was awarded in 1997 to develop British cycling, the ethos of making aggregated small gains in many areas to improve overall performance has been central to its success. Th...

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Abstract In this paper, we introduce the notion of a marginal tube, which is hypersurface foliated by surfaces. It generalises marginally trapped tube and several notions black hole horizons, for example trapping isolated dynamical etc. We prove that if every spacelike section surface, then null. There no assumption on topology tube. To it, study geometry surfaces in four-dimensional spacetime ...

statement of the problem: although all-ceramic restorations are broadly used, there is a lack of information concerning how their fit is affected by fabrication procedure and marginal configuration. purpose: the purpose of this study was to evaluate the marginal fit of zirconia cad/cam ceramic crowns before and after porcelain firing. the influence of finish line configuration on the marginal f...

classes serving at the Company's different Settlements in India arc in existence. The oldest such list which I have ever seen referred to, for I have not myself seen the actual list, is one enumerating the Company's servants serving on the Coast (Madras), and in the Bay (Bengal), in 1652 ; quoted in Yule's notes to Hedge's Diary, Vol. III> P196. This list includes two Medical Officers : At Madr...

introduction: note taking while attending a ppt requires high activity of memory and writing process which ultimately leads to what is called “death by power point” referring to boredom and fatigue. to overcome this we planned to evaluate the impact of utilisation of uncompleted handouts given prior to ppt presentations. methods: final year mbbs students were divided in 2 batches, batch a and b...

background: the inappropriate use of handouts and notes is a common academic problem among students. students' notes are too brief and incomplete in compare with references; hence they may not cover the required content for the courses. the aim of this paper is to analyze students' attitude toward reading handouts and notes instead of references. methods: in this analytical and descri...