Presentation on theme: "Projecting transient populations - pragmatism or technical correctness? BSPS Conference Sep 2004 Richard CooperResearch team Nottinghamshire County Council."— Presentation transcript:
Projecting transient populations - pragmatism or technical correctness? BSPS Conference Sep 2004 Richard CooperResearch team Nottinghamshire County Council
Joint Structure Plan housing figures Regional Planning Guidance (1996-based) – 49,000 dwellings 2001-21 Joint Structure plan accepts total Distribution to sub-areas South Nottinghamshire = 37,000 Nottingham City – supply of 18,500
Population projections for Nottingham City Basis is a ‘set’ number of dwellings Early projections were dwelling-led but – –Migration levels varied widely –Migration-led projection needed –More robust output –More up-to-date information available City wanted age / gender projection
Knowns and unknowns How many houses – but not types of house, household or occupants Age/gender of residents and migrants – but not future migrants Characteristics of residents – but not how those may change
Modelling the population Changing housing provision (e.g. more flats) Assumptions that data in the model will still pertain - –the migration profile remains the same –characteristics (fertility, household generation, etc.) of population remain same for age, gender & relationship
Nottingham city projection – no transient population
Effects of ignoring the transient population Age structure would have many more adults 35-44, (and fewer 15-24) –ageing through fertile and household creation ages For a set number of dwellings (18,500) –8,000 fewer (30% less growth) For a certain migration level –2,500 more dwellings
But why is this a problem (to Notts!) ? Decision to use Patient Register data –From ONS & used in mid-year estimates –More up-to-date –More complete than the Census (includes students) –3 years data - 1997-2000 –More accurate?
A problem ? (2) 3,000 more net in-migrants 15-19 – but are these all students?
A problem ? (3) Transient population used where migration data does not handle flows adequately (1991 Census) If migration data complete there is no need for a transient population - in theory OK However, results did not show sensible outcome – it appeared that some student migrants were being excluded
Determining a transient population Needed a reality check Thought that transient population in CPHM was wrong for application to Patient Register migration How do you decide on a transient population when some information is missing? What should the relevant (20-24) population be doing? It does not remain absolutely constant, even though student numbers may do so – so how does it change? Look at births 20 years ago, not for absolute numbers – but for trends
What the 20-24 year old projectionss should be showing
Changes to 20-24 yr old population 2001 - 2016 Original projection has no transient adjustment May 2003 resulted from City suggestion in setting transient population Mar 2004 accounts for latest information and migration-led projection