Small area demographic projections in Britain
Ludi Simpson and Susan Lomax developed standard methods to project the population and households of areas within a District (or UA), using available data for England, Wales and Scotland. Edge Analytics now offer this service, or users may implement the same methods in-house.
Available data allow a historical time series from 1991 for any set of areas within a District (from 2001 in Scotland), which will be useful to understand past trends as well as help to set future scenarios of fertility, mortality and migration according to each small area’s recent experience.
The population of small areas is relatively volatile compared to that of local authority districts, and is more quickly affected by policy decisions and by economic and environmental change. A standard set of projections using best practice and standard data provides a useful baseline from which other scenarios can be developed. Scenarios often include dwellings-led projections to measure the impact on population of different levels of housing developments.
Any set of area boundaries can be used in principle, as the basic data for population, births and deaths are available for Census Output Areas and Lower Super Output Areas (DataZones in Scotland).
Relevant links:
Documentation
The methods developed at CCSR for areas within local authorities and for National Park areas: Requirements and deliverables; Methods; Reports. Comparison of the results of alternative methods for small area forecasts in Fife Council area, using POPGROUP: Estimation of local demographic variation in a flexible framework for population projections.
Example files
Fife, Scotland, 23 wards: read this first (doc, 14Kb). Example provided by Ludi Simpson, University of Manchester
Files for Population in Fife Wards (zip, 4.2Mb)
Files for Households in Fife Wards (zip, 2.3Mb)
Ashfield, Nottinghamshire, four areas: read this first: (doc, 42Kb). Example provided by Pete Boden, Edge Analytics.
Files for Population in Ashfield areas (zip, 0.9Mb)
Files for Households in Ashfield areas (zip, 1.3Mb)
Scotland
NRS (previously GROS) has supported evaulation of the methods developed at GROS and guidance for using POGROUP and Derived Forecasts software for small area demographic projections. Their site provides details: Scotland datasets and guidance. The household guidance for Derived Forecasts mentions the following files available from this POPGROUP website, relating to the number of people living in Communal Establishments:
2001 Census Table CAS001 Datazones (csv, 4.1Mb; xls on two sheets, zipped 2.4Mb)
Ratio of communal establishments in GROS household projections and the 2001 Census (xls, 0.2Mb)
Services
A service is available, to provide small area forecasts based on these methods, providing the user with finished forecasts and the capability to develop further scenarios: enquiries to popgroup@edgeanalytics.co.uk. The small area projections supplement a service for District projections. Specification and costs will be negotiated in each case.
Other work
Some of the technical challenges were discussed at a POPGROUP meeting in 2004 (http://www.ccsr.ac.uk/popgroup/user/saf.html). Many of these challenges have been overcome in the work described above.
Local area projections were the topic of a special issue of the Journal of Population Research in 2011 (Volume 28, Part 2).