Fertility differentials by urban-rural residence and nativity of women in Australia significantly impact population composition at sub-national levels. We aim to provide consistent fertility forecasts for Australian women characterized by age, region, and birthplace. Age-specific fertility rates at the national and sub-national levels obtained from census data between 1981-2011 are jointly modeled and forecast by the grouped functional time series method. Forecasts for women of each region and birthplace are reconciled following the chosen hierarchies to ensure that results at various disaggregation levels consistently sum up to the respective national total. Coupling the region of residence disaggregation structure with the trace minimization reconciliation method produces the most accurate point and interval forecasts. In addition, age-specific fertility rates disaggregated by the birthplace of women show significant heterogeneity that supports the application of the grouped forecasting method.

翻译：澳大利亚女性城乡居住地与出生地差异导致的生育率差异显著影响着次国家级层面的人口构成。本研究旨在为按年龄、地区及出生地划分的澳大利亚女性群体提供一致的生育率预测。我们采用分组函数时间序列方法，对1981年至2011年人口普查数据中获取的国家及次国家级年龄别生育率进行联合建模与预测。依据选定的层级结构对各地区及出生地女性群体的预测结果进行协调，确保不同细分层级的预测值能够一致地汇总至相应的全国总量。将居住地区细分结构与迹最小化协调方法相结合，可生成最精确的点预测与区间预测。此外，按女性出生地细分的年龄别生育率呈现出显著异质性，这为分组预测方法的应用提供了依据。