Demometric estimation of fertility function by age of women in Poland
Kedelski, M.
Studia Demograficzne 91: 3-24
1988
ISSN/ISBN: 0039-3134 PMID: 12316244 Document Number: 368126
The empirical distribution of age-specific fertility rates in Poland during 1950-1985 and the choice of theoretical distributions to be used in simulation models for prognostical purposes are discussed. The arithmetic mean of the ages of child-bearing women in the given period was 27.33 with a standard deviation of 0.82. The mean age had been decreasing from 28.91 in 1950 to 26.35 in 1980 and remained almost the same until the end of the study period. Total fertility rate, on the other hand, had decreased from 3.68 in 1950 to 2.18 in 1974 and increased slightly afterwards varying between 2.30 and 2.40 in the last four years. The standard deviation of mean age decreased from 6.43 in 1950 to 5.33 in 1985. The statistical analysis of the empirical distribution of age-specific fertility rates lead to the following conclusions: 1. there was an expressed tendency of development in the parameters of the fertility distribution, and 2. the dynamics of the discussed parameters of distribution were strongly correlated. The following theoretical distributions were fitted to the empirical one: Pearson type-I, gamma distribution, and Maxwell distribution. The analysis of statistical parameters demonstrated that the Pearson type-I curve gave the best fit up to 1974 (fitted by Elderton's method). In the 1980's, however, the gamma-distribution gave the best results. Other different functions to be used in modelling the change of fertility rates under European conditions are also mentioned.