Estimation and projection software for general use

Ludi Simpson, University of Manchester

Few projection programs have outlasted the specific applied projects that stimulated them, and fewer have been made available for general use. There are tensions between the technically demanding mathematics for consistent and accurate implementation of demographic dynamics, the requirements these impose on data entered into a projection, and suitability of software used by non-specialists in a variety of data environments. The paper reviews the solutions to these tensions, and details one implementation in the Excel platform which has been taken up by local and national government (www.ccsr.ac.uk/popgroup). Three scenarios are followed: (a) detailed data for each component of change from a national statistics agency, form the basis for critical development; (b) counts of births, deaths and population estimates are sufficient for the software to estimate recent rates of all components, which then drive a forecast; (c) scenarios of future housing determine migration, which the software estimates and compares.