Aalen’s additive Hazard model: an application in analyzing job tenure factors in private and public companies in Albania

Abstract

There are several statistical methods for time to event analysis, among which is the Cox proportional hazards model, that is most commonly used. In this model, the effect of the covariates is assumed to act multiplicatively on the baseline hazard rate and the ratio of the hazards is constant over survival time. However, when the proportionality assumption for the Cox proportional hazards model is not satisfied, an additive hazard regression model may be more appropriate. In this study, we give an overview of this approach and then apply Aalen’s additive hazard regression model to a data set which contain the job tenure for Albanian employees and variables that are thought of as important factors in the job tenure. The Aalen model allows for time-varying covariate effects and is used to assess the impact that age of the employee, the age at which he started the job, salary, gender, position and years of work in front of the current position may have in job termination.