Cohort fertility patterns in Poland based on the staging processes

Wioletta Grzenda, Warsaw School of Economics
Ewa Fratczak, Warsaw School of Economics

A staging process is defined as a chain of elementary processes. This process is frequently used in life course analysis, because many episodes of individual life can be described using it. Examples of staging process in life course might be: a migration process or a fertility process, which analysis is the aim of this presentation. We will consider the time from the age of 15 to first child birth, from first child birth to second and so on. So, the elementary process repeats itself after each occurrence of event, which is child birth. The events occur in specified order and multiple occurrences are impossible. We consider Poisson process with times between two successive events, called waiting times, being independent variables with exponential distribution with different parameters. The analysis of changing the fertility patterns in Poland by generations 1931-1986 is based on stochastic life tables estimate for five age groups. The empirical data comes from the sample survey “Female Fertility” conducted by the Central Statistical Office in Poland in 2002 . The sample size is ca. 276 thousands females aged 16 and over. The main point of this work is presentation of the vales of stage probabilities of the subsequent births for these five age groups: 15-19, 20-24,…, 45-49. The results show the changes in fertility patterns in Poland during the period under studies.