Integration of Estimates within Population Projections

Ludi Simpson, Cathie Marsh Centre for Census and Survey Research

The inclusion of estimated data in a projection allows increased accuracy in the early years of a projection, and the estimation within the model of back-projected rates and flows. These provide a demographic database for better judgement of likely future rates. The forecast is trained using all the available information including that beyond the base year. Estimates provide constraints on a population projection. Simple mathematical solutions will be illustrated with reference to the generic projections software POPGROUP. This software (http://www.geocities.com/popgp2002/) was developed by and for local government in the UK, and is used additionally in academic teaching. A variety of applications for regions of the UK will end the paper: (a) integrating vital statistics into a projection for local areas. (b) integrating post-census population estimates to improve migration assumptions. (c) integrating diverse datasets available for a projection of ethnic groups. (d) integrating housing plans into a population projection.