Super Output Areas for Neighbourhood Statistics

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Super Output Areas for Neighbourhood Statistics

• Robert Heyward / Nick Stripe

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Outline

• Sub-Regional and Sub-District Geographies
• NeSS Geography Policy
• Census Output Areas
• Super Output Areas
• principles
• lower and middle layers
• Consultation - Pilot
• Decisions on Consultation and Timing
• Future Review
• Recognised Issues

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National / Regional, District and Sub-District
Geographies (England and Wales)
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Geography Policy

• Emphasis on stability
• improving our ability to measure change over time
• Use of standard geographic units
• Grid reference
• Output areas
• Super Output areas
• Districts
• Statistics built from these blocks
• or by estimation for other areas

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Geography Policy
Standard geographic units
Districts
Frozen bases for data collection output
Super OAs
Output Areas
Estimates for User Defined Areas fitted groups
of OAs
Grid reference
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Census Output Areas

• New for 2001 Census (EW), a geography
  specifically for low-level census outputs.
• approximately 175,000 OAs in England Wales
• align with administrative boundaries (Wards,
  Civil Parishes)
• built from unit postcodes on Census day. (April
  29th 2001) split for wards etc

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Geography Policy for NeSS

• Output Areas valued because
• Small - provide focus
• Stable - help with time series
• Stable - ease integration
• Stable - can act as a building brick
• Homogeneous - reflect the real world
• Help with disclosure
• Independent

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Why Super Output Areas are required

• Sub-district geography of electoral wards is poor
  
• variation in size lt 1,000 to gt 30,000 residents
• ward boundaries change over time (periodic
  review)
• Census OAs
• good, but too small for many non-Census sources
• Super OAs
• comparability is fairer as sizes are more
  similar,
• enables ready comparison over time - durable
• helps to address disclosure control issues
• build on availability of data for census output
  areas

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Super Output Areas - diagram
Districts ??
link to districts? 3 intermediate layers lowest
level nesting in wards all built from Census OAs
Upper min 25,000
Middle min 5,000
Wards
Lower min 1,000
Output Areas
Grid reference
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Principles

• affirmed in consultation spring 2003
• feasibility study March - June 2003
• advisory groups July, Aug 2003
• lower layer
• zone design
• relationship with wards at outset
• influence of similarity of size, proximity and
  homogeneity
• connectedness (not developed in time)
• middle layer
• zone design plus local modification
• upper layer
• now decoupled (method to be reconsidered)

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Lower layer SOAs

• c. 35,000 zones
• set by zone design software
• average 1500 residents
• 58 between 1400 and 1600
• 97 between 1000 and 2000
• only 0.1 over 3000
• nest within Census ST wards
• used for Indices of Deprivation
• NOT for consultation in 2004
• for review and possible modification in 2006

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Zone design software example Greenwich lower
layer SOAs (part)
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Middle layer SOAs

• for modification locally in 2004
• software default - c. 7,000 zones
• average 7500 residents
• 52 between 7000 and 8000
• 97 between 5000 and 10000
• one above 15000
• nest within district
• not constrained to ward boundaries
• 26 within a single (large) ward
• 74 straddle ward boundaries

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Zone design software example Greenwich middle
layer SOAs
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(No Transcript)
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Local consultation - pilot

• August / September 2003
• 9 LAs Birmingham to Cornwall
• asked to modify middle layer
• where boundaries split estates / settlements
• some rectified by local modification
• sometimes lower layer hinders desired middle
  layer
• SOAs and user defined areas
• SOAs statistical units NOT neighbourhoods
• better estimate for user defined areaif SOA
  avoid splitting areas of interest

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Consultation NeSS Programme Board Decisions

• Lower layer published Jan 2004
• at this stage NOT for consultation
• middle layer for consultation early 2004
• BOTH lower and middle layers reviewed in 2006
• with option of second set of zones (if then
  considered appropriate)
• between now and 2006, opportunity for learning
• to improve the usability of the SOAs
• all feedback welcomed

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Middle layer consultation - timing

• Announce and publicise - January
• Local co-ordinators identified - February
• download materials from website - March
• local discussion of modifications March - May
• final date for return to ONS - May
• national set assembled - June
• with automated zone design if no modifications
• issued to data suppliers - August onwards
• NeSS website shows data for SOAs - early 2005

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Why consult at middle layer?

• make use of local knowledge
• adapt automated proposals
• allow greater variation of size within range
• allow more or fewer zones
• improve approximate fit with recognised features
• improve approximate fit with areas of interest
• allow optional constraints to wards if locally
  desired
• more manageable in timescale with central and
  local resources available
• anticipated that most data will be made available
  at this level

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Recognised Issues

• Why base SOAs on Census OAs?
• Why not consult at the lowest level?
• Arent these SOAs meant to reflect communities?
• How are user defined geographies going to work?

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Why base them on Census OAs ?

• Because of synergies with Census and associated
  release of data
• Census data critical as reliable denominators for
  NeSS (and other purposes)
• CRITICALLY - because Census data could not be
  re-released for any other small geography
  (disclosure issues)
• We are fully aware that this brings with it some
  of the quirks of OAs

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Why not consult on the lowest level ?

• The size and complexity of the task
• 175,000 Output Areas 35,000 lower layer Areas
• The timetable
• established for data collection by mid 2004
• The view of the Advisory Group
• keep it simple, move fast and establish stability
• Two-year research projects . Delivery 2006
• Half the decade will have passed.
• View of NeSS PB
• move quickly to gain experience with data
• review in 2006

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Arent these SOAs meant to reflect communities?

• No- avoid problems with wards- allow change to
  be monitored at focussed level
• They are a statistical geography- must balance
  data availability (without disclosure)
• They are a national geography- must balance
  comparability
• What is a community? Whose communities?
• Building blocks from which local statistics can
  be flexibly created

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How are user defined geographies going to work ?
Output of COUNT - OAs, SOAs, LADs
An output built by adding up data collected for
the frozen block geography
Choose dataset(s)
Choose year(s)
Choose area
Output of BEST FIT ESTIMATE for area
An output built by estimating from the blocks for
an area that isnt an exact fit.
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Further information and Contacts

• for lower layer definition
• http//www.statistics.gov.uk/geography/soa.asp
• ONS Customer Contact Centre
• 0845 601 3034
• http//www.statistics.gov.uk/email.asp
• Super Output Areas
• - Robert Heyward robert.heyward_at_ons.gov.uk
• - 020 7533 6115
• Consultation Process
• Nick Stripe nicholas.stripe_at_ons.gov.uk
• 01329 813131