Summary and Closing Thoughts Greg Ball BSPS Council Member Variant Projections Summary and Closing Thoughts Greg Ball BSPS Council Member

Variants – what users do “In the absence of any clear guidance ... users take one of two courses of action. Either they reduce the uncertainty by ignoring all the scenario variations ... and simply take the central projection, Or... choose whichever end of the range justifies the taking of a particular policy position...” Keith Woodhead 1985

Migration - a longstanding problem “...imbalance between the relatively well-developed theory of demographic change and the relative paucity of explanation of migration...” “...outstanding uncertainties ... as to how best to integrate and make consistent the estimation of population and migration change with the anticipated effects of policy.”

Approaches to internal migration Demographic Multi-zonal (e.g. ONS) Origin to Destination, based on recent patterns Age the key determinant of flows Changes in origin populations drive future migration flows Consistent but inflexible Local Demographic (e.g. POPGROUP) Allows scenarios –e.g. Housing development rates Effects on other areas?? Inconsistent across country Integrated multi-zone models E.g. East of England Forecasting Model

Local Housing Scenarios - Get in line! Models assume an orderly queue. Local household formation International and cross-border migration Internal migration between local authorities To match housing scenario Adjust internal flows (in and/or out)

Housing The True Story There is no queue Who pays wins

Issues for local scenarios How can we better model relationships between policies for new housing development and migration? What are the relationships, if any, between migration to and from an area and local household formation? How do we model effects of local scenarios on other areas?