The semi-parametric Cox proportional hazards (PH) regression model was developed by Sir David Cox (Cox 1972) and is by far the most popular model for survival analysis. The model defines a hazard function, which is the rate of an event occurring at any given time, given the observation is still at risk, as a function of the observed covariates. When data consist of independent and identically d...

tires represent a critical spare part in mines. there is a shortage of medium and large tires. in addition, with increased mining activities and the creation of new mines, the demand for tires has increased significantly. thus, it is particularly important for mining engineers to identify tire characteristics and correctly manage the spare part inventory. spare parts management is critical from...

For the final reduced multivariate Cox proportional hazards model presented in Table 3 of the main text, we assessed the proportional hazards assumption via the Schoenfeld residuals. We examined plots of the residuals for each variable against time to check for a non-­‐zero slope, which indicates that the proportional hazards assumption is violated (Hosmer et al. 1999). We then performed statis...

The use of the Cox proportional hazards regression model is widespread. A key assumption of the model is that of proportional hazards. Analysts frequently test the validity of this assumption using statistical significance testing. However, the statistical power of such assessments is frequently unknown. We used Monte Carlo simulations to estimate the statistical power of two different methods ...

The accelerated failure time (AFT) model is an important alternative to the Cox proportional hazards model (PHM) in survival analysis. For multivariate failure time data we propose to use frailties to explicitly account for possible correlations (and heterogeneity) among failure times. An EM-like algorithm analogous to that in the frailty model for the Cox model is adapted. Through simulation i...

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 ...

Line 54: How is the variant associated with mean telomere length? Is it associated with increased/decreased length? The A allele of rs2736100 was associated with decreased telomere length. This is described in the last paragraph of the Background section. Methods Line 144: Should read “Six SNPs” rather than “Six (6) SNPs”. This error has been corrected. State whether the assumptions of the cox ...