The constant baseline hazard assumption was next evaluated to assess whether the hazard rate varied significantly across this time frame (i.e. across ages). The unconditional hazard model (with time-varying hazard rates) was found to significantly improve fit compared to a model that constrained the hazard rate to equality (χ2 = 77.55, df=9, p<.001). Thus, the constant baseline hazard assumption was rejected and the hazard function was allowed to vary across age in all models.
