The inefficiency of the immigration-based demographic equilibrium

This study investigates the impact that a possible increase in fertility rates and the control of immigration have on population stationarity following the approach used in Angrisani and Di Palo (2016). Our paper shows that using immigration for population stationarity leads to a gross inefficiency in terms of size and age distribution of the stationary population. Indeed, we show that immigration-based population stationarity is inefficient as the stationary population results in having a larger size than that obtained bringing the fertility rates to the whole natural level of equilibrium. Furthermore, the immigration-based stationary population results in being unbalanced in terms of ratios between old and young age groups pro the former ones. In order to perform population evolution, the Leslie model has been used in a two sex form already applied in a previous work, and in order to introduce the effect of possible changes in fertility or immigration in the model the modified approach of Angrisani and Di Palo (2016), has been used in a slightly simplified version. Numerical illustration is obtained on data by gender for the Italian population.