Stratified-extended cox model in survival modeling of non-proportional hazard

Abstract Cox proportional hazard model is frequently used in survival analysis. Cox proportional hazard model is time independent covariate while many models involve time as a dependent covariate causing incomplete proportional hazard assumption, known as non-proportional hazard. The proposed model in this paper was a non-proportional hazard involving time-independent and time-dependent covariates. The approaching model was carried out by joining a stratified Cox and extended Cox model termed as Stratified-Extended Cox (SE Cox) model. The simulation of the SE Cox model resulted in small MSE for the parameter estimates. In addition, the goodness of value was more appropriate compared to the existing non-proportional hazard model. Hence, the SE Cox model was applied to evaluate student persistence in Universitas Terbuka, Indonesia.