Projecting fertility using synthetic parity progression ratios, with application to Australia and Iran

Peter McDonald, Australian National University
Rebecca Kippen, Australian National University
Bruce Bacon, Australian National University
Meimanat Hossein Chavoshi, Australian National University
Mohammad J. Abbasi-Shavazi , University of Tehran

The authors have constructed annual synthetic parity and duration specific progression ratios for Australia and Iran. The basic unit is: q(i,j,t) = the probability that a woman of parity i whose previous birth occurred j years ago will advance to parity i+1 in year t. We have calculated these probabilities for Australia and Iran for single calendar years from 1980 to 2000, for single parities and for single years of duration since the last birth. Analyses of these data and aggregated measures derived from them show that interpretations of trends can be placed much more effectively within the framework of the tempo and quantum of fertility than is the case for synthetic age-based measures. Here, we test the efficacy of various methods of projecting q(i,j.t) and their aggregates to obtain projections of cross-sectional fertility. We employ both time series approaches and expert knowledge, including information on birth intentions.