Cox and Frailty Models for Analysis of Esophageal Cancer Data‎

ýBy existing censor and skewness in survival dataý, ýsome models such as weibull are used to analyzing survival dataý.
ýIn addition, parametric and semiparametric models can be obtained from baseline hazard function of Cox model to fit to survival dataý. ýHowever these models are popular because of their simple usage but do not consider unknown risk factorsý, ýthat's why cannot introduce the best fit to the data necessarilyý.
ýIn this paper by considering multiple random effects in Cox modelý, ýfrailty models are introducedý. ýThen using presented modelsý, ýesophageal cancer data in Golestan were modeled and fitted models were evaluated and compared based on generalized coefficient of determination criterioný.