Penalised maximum likelihood estimation in multi-state models for interval-censored data

Continuous-time multi-state Markov models can be used to describe transitions over time across health states. Given longitudinal interval-censored data on transitions between states, statistical inference on changing health is possible by specifying models for transition hazards. Parametric time-dependent hazards can be restrictive, and nonparametric hazard specifications using splines are presented as an alternative. The smoothing of the splines is controlled by using penalised maximum likelihood estimation. With multiple time-dependent hazards in a multi-state model, there are multiple penalty parameters and selecting the optimal amount of smoothing is a challenge. A grid search to estimate the penalty parameters is computational intensive especially when combined with methods to deal with interval-censored transition times. A new and efficient method is proposed to estimate multi-state models with splines where the estimation of the penalty parameters is automatic. A simulation study is undertaken to validate the method and to illustrate the effect of interval censoring. The feasibility of the method is illustrated with two applications

Проблемні питання щодо паспортизації об’єкта історії “Місце битви польсько-шляхетської армії із військами Остапа Гоголя”

Reduced memory specificity is associated with depression, post-traumatic stress disorder (PTSD), and some other forms of psychopathology. Reduced memory specificity is also associated with reduced specificity of envisioned future events. Research in this area has mostly relied on cue-word methods that include explicit instructions to develop specific memories of future events. These methods are limited in their ability to assess how participants habitually remember the past and imagine the future when the specificity constraints inherent in the cue-word task are removed. Sentence completions tasks have been developed that can be used to assess habitual patterns of memory and prospection. Little is known about the association of habitual memory and prospection with concurrently and prospectively assessed psychopathology. In the current study 142 participants completed sentence completion tasks tapping habitual memory and prospection at baseline and completed measures tapping psychological symptoms at baseline and 1 year later. Among other things, it was found that reduced memory specificity (but not reduced future specificity) was associated with concurrent and later depression, as well as with symptom levels of PTSD tapped 1 year beyond baseline

Joint models for discrete longitudinal outcomes in ageing research

Given the aging population in the UK, statistical modelling of cognitive function in the older population is of interest. Joint models are formulated for survival and cognitive function in the older population. Because tests of cognitive function often result in discrete outcomes, binomial and beta–binomial mixed effects regression models are applied to analyse longitudinal measurements. Dropout due to death is accounted for by parametric survival models, where the choice of a Gompertz baseline hazard and the specification of the random-effects structure are of specific interest. The measurement model and the survival model are combined in a shared parameter joint model. Estimation is by marginal likelihood. The methods are used to analyse data from the Cambridge City over-75s cohort study and the English Longitudinal Study of Agein

Transitions across cognitive states and death among older adults in relation to education: a multi-state survival model using data from six longitudinal studies

Introduction: This study examines the role of educational attainment, an indicator of cognitive reserve, on transitions in later life between cognitive states (normal Mini-Mental State Examination (MMSE), mild MMSE impairment, and severe MMSE impairment) and death. / Methods: Analysis of six international longitudinal studies was performed using a coordinated approach. Multistate survival models were used to estimate the transition patterns via different cognitive states. Life expectancies were estimated. / Results: Across most studies, a higher level of education was associated with a lower risk of transitioning from normal MMSE to mild MMSE impairment but was not associated with other transitions. Those with higher levels of education and socioeconomic status had longer nonimpaired life expectancies. / Discussion: This study highlights the importance of education in later life and that early life experiences can delay later compromised cognitive health. This study also demonstrates the feasibility and benefit in conducting coordinated analysis across multiple studies to validate findings

Окрема думка судді в кримінальному процесі

З’ясовується змістове наповнення правових засад, на підставі яких суддя може викласти окрему думку. Досліджується поняття «окремої думки судді» в різних країнах та правових системах. Висвітлюється механізм реалізації окремої думки судді в порівнянні з правом зарубіжних держав та вносить пропозиції щодо запозичення та ведення аналогічних механізмів реалізації окремої думки судді в Україні.Раскрывается содержание правовых принципов, на основании которых судья может изложить особое мнение. Исследуется понятие «особого мнения судьи » в разных странах и правовых системах. Освещается механизм реализации особого мнения судьи в сравнении с правом зарубежных государств и вносит предложение относительно заимствования и ведения аналогичных механизмов реализации особого мнения судьи в Украине.This article investigated the legal principles on which the judge may express the separate opinion; the existence of the notion of «the separate opinion of judge» in different countries and legal systems is conducted. The author analyzed the mechanism of realization of the separate opinion of judge in comparison with the law of foreign countries and made proposals for borrowing and introduction of the similar mechanisms for realization the dissenting the separate opinion of judge in Ukraine

A mixture model for the joint analysis of latent developmental trajectories and survival

A general joint modeling framework is proposed that includes a parametric stratified survival component for continuous time survival data, and a mixture multilevel item response component to model latent developmental trajectories given mixed discrete response data. The joint model is illustrated in a real data setting, where the utility of longitudinally measured cognitive function as a predictor for survival is investigated in a group of elderly persons. The object is partly to determine whether cognitive impairment is accompanied by a higher mortality rate. Time-dependent cognitive function is measured using the generalized partial credit model given occasion-specific mini-mental state examination response data. A parametric survival model is applied for the survival information, and cognitive function as a continuous latent variable is included as a time-dependent explanatory variable along with other explanatory information. A mixture model is defined, which incorporates the latent developmental trajectory and the survival component. The mixture model captures the heterogeneity in the developmental trajectories that could not be fully explained by the multilevel item response model and other explanatory variables. A Bayesian modeling approach is pursued, where a Markov chain Monte Carlo algorithm is developed for simultaneous estimation of the joint model parameters. Practical issues as model building and assessment are addressed using the DIC and various posterior predictive tests