A family of tests for the presence of regression effect under proportional and non-proportional hazards models is described. The non-proportional hazards model, although not completely general, is very broad and includes a large number of possibilities. In the absence of restrictions, the regression coefficient,   t  , can be any real function of time. When   , t    we recover the propo...

We propose a new method for variable selection and estimation in Cox's proportional hazards model. Our proposal minimizes the log partial likelihood subject to the sum of the absolute values of the parameters being bounded by a constant. Because of the nature of this constraint it tends to produce some coeecients that are exactly zero and hence gives interpretable models. The method is a variat...

Results. Of the 18,602 identified patients, there was a 5.2% Study Design. Retrospective review of a prospective cohort. Objective. The aim of the study was to determine the patient characteristics and surgical procedure factors related to increased rates of 30-day unplanned readmission and major perioperative complications after spinal fusion surgery, and the association between unplanned read...

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...

This article investigates the value of perfect monitoring information for optimal replacement of deteriorating systems in the Proportional Hazards Model (PHM). A continuous-time Markov chain describes the condition of the system. Although the form of an optimal replacement policy for system under periodic monitoring in the PHM was developed previously, an approximation of the Markov process as ...

This article addresses a connection between the Bradley and Terry (1952A) model and Cox (1972) proportional hazards model. We show that the partial likelihood of random variables that satisfy the stratified proportional hazards assumption of Cox (1972) coincides with the likelihood given by the Bradley-Terry (BT) model for rank order events. Such a connection not only allows many available soft...

Probabilistic models for biological sequences (DNA and proteins) have many useful applications in bioinformatics. Normally, the values of parameters of these models have to be estimated from empirical data. However, even for the most common estimates, the maximum likelihood (ML) estimates, properties have not been completely explored. Here we assess the uniform accuracy of the ML estimates for ...

The analysis of high-dimensional survival data is challenging, primarily owing to the problem of overfitting, which occurs when spurious relationships are inferred from data that subsequently fail to exist in test data. Here, we propose a novel method of extracting a low-dimensional representation of covariates in survival data by combining the popular Gaussian process latent variable model wit...

This study examines what neighborhood conditions experienced at age 15 and after are associated with teen childbearing and fathering among Latino and African American youth and whether these neighborhood effects vary by gender and/or ethnicity. Administrative and survey data from a natural experiment are used for a sample of 517 Latino and African American youth whose families were quasi-random...

BACKGROUND The impact of moving to a neighborhood more conducive to utilitarian walking on the risk of incident hypertension is uncertain. OBJECTIVE Our study aimed to examine the effect of moving to a highly walkable neighborhood on the risk of incident hypertension. METHODS A population-based propensity-score matched cohort study design was used based on the Ontario population from the Ca...