Polynomial splines are used to estimate the log-hazard function based on possibly censored, positive data. Two additional log terms are incorporated into the fitted model for the log-hazard function to allow for greater flexibility in the extreme tails. A fully automatic procedure involving the maximum likelihood method, stepwise knot addition, stepwise knot deletion and BIC is used to select t...

Objective To assess the characteristics of biochemical recurrence in the late period (>5 years after radical prostatectomy) and the differences in the predictors of biochemical recurrence in different periods, we conducted a multicenter retrospective study. Methods We reviewed 478 men who underwent radical prostatectomy for clinically localized prostate cancer. All of the patients were follow...

residential location choice modeling is one of the areas in transportation planning that attempts to examine households location search behavior incorporating their trade-offs between housing quality, prices or rents, distance to work and other key factors. this brings up the need to come up with methods to logically allocate credible choice alternatives for individuals.this article attempts to...

In survival analysis, a competing risk is an event whose occurrence precludes the occurrence of the primary event of interest. Outcomes in medical research are frequently subject to competing risks. In survival analysis, there are 2 key questions that can be addressed using competing risk regression models: first, which covariates affect the rate at which events occur, and second, which covaria...

Models generally consider risk to be a function of the hazard (toxicity) and exposure (dose). That function is best described by the dose response of the toxic effect. For any risk assessment system to be effective, it should consider that dose-response relationship. Saturation phenomena often produce nonlinear dose curves, and any risk assessment system should be able to address such effects. ...

Interval censored outcomes arise when a silent event of interest is known to have occurred within a specific time period determined by the times of the last negative and first positive diagnostic tests. There is a rich literature on parametric and non-parametric approaches for the analysis of interval-censored outcomes. A commonly used strategy is to use a proportional hazards (PH) model with t...

abstract background: keratoconus is a bilateral corneal disease, which one way to cure it is to transplant. the transplantation may be rejected by recipient's immune system, which leads to failure of the graft. this study aimed to analysis the factors affecting bilateral corneal graft rejection based on copula function. methods: a sample of bilateral graft rejection times was assessed. since co...

the data set employed in this study was comprised of a number of 6,800 records of lamb’s longevity and their survival rate, collected from 1989 through 2009, from the lori-bakhtiari experimental flock at the shooli station in shahrekord, iran. the data were analyzed using linear models and proportional hazard models with weibull function. these models included fixed factors and direct additive ...