Estimation of foreigner's fertility in Italy using mathematical functions

Giuseppe G. De Bartolo, Universita della Calabria
Manuela Stranges, Universita della Calabria

The data about immigrant population currently available in Italy allow prompt study of the most important demographic phenomena, but difficulties arise at the level of single nationalities. This is a first attempt to estimate age specific fertility rates of some foreign nationalities in Italy. The method proposed bypasses these difficulties using fertility theoretical curves, which depend on three demographic indices: total fertility, average age at childbearing, variance around this average age. The theoretical curves used are: Beta, Gamma, Lognormal, Third-degree Polynomial, Hadwiger, from which we have chosen the best fitting function. Comparing real and estimated values we can state that the best function is Beta. As the data will become more reliable the proposed procedure could give better results; also, it will be possible to take into consideration other functions than those proposed here and to try to estimate the fertility curves of other Italian immigrant populations.