Reconstructing the past using multistate population projections: the example of religious denominations in the City of Vienna from 1971 to 2011

Anne Goujon, Wittgenstein Centre (IIASA, VID/ÖAW, WU)
Ramon Bauer, Wittgenstein Centre (IIASA, VID/ÖAW, WU)

The study describes the procedure to reconstruct the single year population in single year steps using multistate population projections, making use of the wealth of information on religious denominations available through censuses on the city of Vienna in Austria: population by age (5-year age groups), sex, and religious denomination every ten year from 1971 to 2011, absolute numbers of Church ‘leavers’, births by woman’s religion). Estimates are produced for the different parameters: splitting 5-year age-groups into single year, estimating migration by religion, and defining age-schedules of most events i.e. fertility and migration. We do not assume any mortality differentials by religious denominations. The methodology proceeds by iteration using multistate projections and allows reconstructing the detailed landscape of the religious denominations in the last 40 years together with the main determinants of change in terms of migration and fertility. The method can be extended to other historical reconstruction with partial data.