Calculating fertility rates using the Office for National Statistics Longitudinal Study for England & Wales
Robards, J.W. (2010) British Society for Population Studies Annual Conference, University of Exeter, UK, 13 - 15 September 2010 [ONS LS]
The Office for National Statistics Longitudinal Study for England and Wales is a large, linked dataset composed of a 1% sample of the population. Given the large sample size that this dataset offers for analysis there has been a tendency for researchers to assume that the LS is representative of the population of England and Wales. This is unlikely to be the case, for example, reports from the Office for National Statistics show that there is a lower rate of census-to-census linkage for specific members of the LS. Building on existing knowledge, this paper hypothesises idealised residence ‘trajectories’ for female LS members in the 1991-2001 period. LS members are attributed to each of the trajectories created and hence we are able to estimate the proportion of LS members who have incomplete information, for example because they make an unrecorded embarkation from the LS in the 1991-2001 period. The various residence trajectories are used to calculate numbers of women in the LS who are exposed to risk of giving birth, and the number of births to these women in the LS. Hence we estimate fertility rates for women according to their residence trajectories. Indeed, the LS is a suitable dataset for understanding the fertility of recent migrants as through registration with a General Practitioner new migrants to England and Wales are added to the LS. Through the accurate calculation of women exposed to risk of birth it is possible to understand precise residence trajectories and subsequent fertility for LS members who migrated to England and Wales.