The life cycle cost of a system is influenced by its maintainability. Maintainability is a design parameter, whose operational conditions can affect it significantly. Hence, the effects of these operational conditions should be quantified early in the design phase. The proportional repair model (PRM), which is developed based on the proportional hazard model (PHM), can be used to analyze mainta...

Relatively there is little empirical research that has been taken to understand how the underlying economy affects customers’ subsequent financial product purchase behaviours. A better understanding of this influence and being able to predict the probability of purchasing are important for financial service industries. This paper undertakes an examination of the impacts of social-demographic an...

Identification of long-term risk factors after heart valve replacement can be quite challenging due to the nature of the covariates. Two specific factors need to be considered : (1) time-dependent covariates, and (2) the validity of the proportional hazard model. PHREG in SAS® is a very convenient procedure for solving these problems. In addition to those commonly encountered problems such as v...

Background & Aims: Renal transplantation is the best therapeutic option for End Stage Renal Disease (ESRD). The aim of this study was to determine the graft survival rate of renal transplantation in patients who have been transplanted from live donor in Shiraz Transplant Research Center, Shiraz, Iran. Methods: In a survival analysis study, organ survival rate after kidney transplantation from...

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 ...

BACKGROUND Randomized Controlled Trials almost invariably utilize the hazard ratio calculated with a Cox proportional hazard model as a treatment efficacy measure. Despite the widespread adoption of HRs, these provide a limited understanding of the treatment effect and may even provide a biased estimate when the assumption of proportional hazards in the Cox model is not verified by the trial da...

Skewed data is the main issue in statistical models in healthcare costs. Data transformation is a conventional method to decrease skewness, but there are some disadvantages. Some recent studies have employed generalized linear models (GLMs) and Cox proportional hazard regression as alternative estimators. The aim of this study was to investigate how well these alternative estimators perform in ...

Simulation studies present an important statistical tool to investigate the performance, properties and adequacy of statistical models in pre-specified situations. One of the most important statistical models in medical research is the proportional hazards model of Cox. In this paper, techniques to generate survival times for simulation studies regarding Cox proportional hazards models are pres...