BACKGROUND Heart failure survival models typically are constructed using Cox proportional hazards regression. Regression modeling suffers from a number of limitations, including bias introduced by commonly used variable selection methods. We illustrate the value of an intuitive, robust approach to variable selection, random survival forests (RSF), in a large clinical cohort. RSF are a potential...

Gu and Zheng (1993) established a Bartlett adjustment for the partial likelihood ratio test in the Cox proportional hazards regression model. It is known that the same method of adjustment cannot be used to improve the accuracy of the test statistic derived by Rao’s score method. In this paper, the method of Cordeiro and Ferrari (1991) is used to derive a Bartlett type correction for the score ...

A major assumption of the Cox proportional hazards model is that the effect of a given covariate does not change over time. If this assumption is violated, the simple Cox model is invalid, and more sophisticated analyses are required. This paper describes eight graphical methods for detecting violations of the proportional hazards assumption and demonstrates each on three published datasets wit...

The joineR package implements methods for analysing data from longitudinal studies in which the response from each subject consists of a time-sequence of repeated measurements and a possibly censored time-toevent outcome. The modelling framework for the repeated measurements is the linear model with random effects and/or correlated error structure. The model for the time-to-event outcome is a C...

BACKGROUND Most randomized controlled trials with a time-to-event outcome are designed assuming proportional hazards (PH) of the treatment effect. The sample size calculation is based on a logrank test. However, non-proportional hazards are increasingly common. At analysis, the estimated hazards ratio with a confidence interval is usually presented. The estimate is often obtained from a Cox PH ...

Cox proportional hazards (PH) regression is a well-known model for analyzing survival data and its strengths are widely recognized. Threshold regression (TR) is a relatively new methodology but one that is receiving greater attention and being used successfully by researchers in different fields, including biopharmaceutical statistics. In threshold regression, event times are modeled by a stoch...

patients and methods this was a historical cohort study. a total of 1396 patients admitted between march 2011 and march 2012 in 16 mmt clinics (13 private and 3 state clinics) in rafsanjan, entered the study and their retention rate was examined for one year. the patients’ data abstracted from their medical records using checklists and collected by clinics’ staff. data analyses were performed u...