National versus local projections Keith Woodhead Understanding Local Population Projections SW Observatory 8 th September 2010
Why project? <ul><li>Short to medium term projections (time horizon <10 yrs) detailed forecasts for service planning & delivery </li></ul><ul><li>Longer term projections (10-25 yrs) strategic planning applications (eg LDF Core Strategies & long term infrastructure investment) </li></ul><ul><li>Long range scenarios (typically up to 30-40 yrs) exploring possible future policy contexts or to test robustness of existing plans (eg impacts of climate change on infrastructure, rising energy costs on travel behaviour) </li></ul><ul><li>But also </li></ul><ul><li>Population Projections as technical inputs to other models eg to help estimate household demand and labour supply components of economic forecasts/ projections or household trip behaviour in transport models </li></ul>
What does ONS provide? <ul><li>National projections – every 2 years – latest (2008 based) published Oct2009, variant projections Nov ‘09) single projection years 2008-33 (5 yrly 2036-56, selected yrs to 2083), 1 and 5 yr age cohorts details http://www.statistics.gov.uk/downloads/theme_population/NPP2008/NatPopProj2008.pdf </li></ul><ul><li>Sub national projections – every two years – latest (2008 based) published May 2010, 5yr age groups by GOR, LA, SHA, PCOs* by single years to 2033 http://www.statistics.gov.uk/downloads/theme_population/snpp-2008/InteractivePDF_2008-basedSNPP.pdf </li></ul><ul><li>‘ Spin-off’ projections: </li></ul><ul><ul><li>DCLG Household projections –trail the sub natl ONS projection by c 6 months; covers GORs, LAs; 2008 based expected Oct/Nov 2010 http://www.communities.gov.uk/publications/corporate/statistics/2026households0208 </li></ul></ul><ul><ul><li>ONS Labour force projections – occasional, last publ Jan 2006 (2004 based) http://www.statistics.gov.uk/articles/nojournal/labour_force_projections_06-20/projections_fullreport.pdf </li></ul></ul><ul><ul><ul><li>AND don’t forget, lastest updates accessible via the SWO help page: http://www.swo.org.uk/resources/data-releases/population/ </li></ul></ul></ul><ul><li>* PCO = Primary Care Organisation (yes, I had to look it up too) </li></ul>
So, with all this ONS material, why do we need local projections? Austerity Government CSR10 -25%£ Local Projections? Bah! Humbug DCLG
National v local projections <ul><li>National beats local </li></ul><ul><ul><li>Consistency of assumptions between areas </li></ul></ul><ul><ul><li>Subject to national peer review </li></ul></ul><ul><ul><li>Adds to a generally reliable regional/ national total </li></ul></ul><ul><ul><li>Avoids most local policy ‘optimism bias’ </li></ul></ul><ul><li>Local beats national </li></ul><ul><ul><li>Reflects local knowledge, particularly impact of local migration, development proposals, local policy change </li></ul></ul><ul><ul><li>‘ Hands on’ use for testing policy scenarios etc & sensitivity testing and can be tailored for local decision making </li></ul></ul><ul><ul><li>Can be more accurate over short to medium term, but not necessarily in aggregate (‘optimism bias’ problem) </li></ul></ul><ul><li>Conclusion: The two sources are complementary and can ultimately help save resources </li></ul>
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