Immigration and the dependency ratio of a host population

This paper examines the long-term impact of constant immigration on the dependency ratio in an SI population (a stationary population through constant immigration) in the context of the stable population model. Our analysis has three main findings. First, in SI populations, a younger population (a lower aging ratio) does not necessarily have a lower dependency ratio. An SI population has a lower dependency ratio than a closed stationary population, provided immigration is concentrated around the youngest working age in the host population. Second, under the same condition, selecting high-fertility immigrants increases the dependency ratio. Third, also under the same condition, substituting working-age immigrants with young (dependent) immigrants increases the dependency ratio. Using the United Nations model age structures of immigrants, our empirical illustration confirms these analytical results.