1. England and Wales Grid Map
Andy Tait,
Office for National Statistics,
12th March 2009

2. What I’ll cover
Small area statistical geography in England and Wales
Geography Policy for statistics
Measuring population in England and Wales
The E&W Grid Map (at last!)

3. UK Geography – why it’s a problem
There are a lot of them
They change all the time
Postcodes/addresses
Boundary change
New geographies
They do not align with each other
Different codes/names used to describe them

4. I now wish to take you through our assessment of the options
Thank you Lionel
I now wish to take you through our assessment of the options 17 16

5. Range of UK Geographies
Parishes
Wards
LADs
Counties
GORs
Countries
Registration Dists
National Parks
TTWAs
LLSCc
LEAs
etc.
PCOs
SHAs
Pan SHAs
LHBs
CHPs
HBs
HSSBs
NUTS 1-5
LAU 1-2
Westminster Parli Cons
NAW Cons/Regions
Scottish Parli Cons/Regs
European Electoral Regs

6. Avon
1995 19

7. 19

8. Yorkshire and
Humberside 19

9. Yorkshire and
Humber 19

10. Yorkshire and
the Humber 19

11. Yorkshire and
The Humber 19

12. RICHMOND UPON THAMES 17 Thank you Lionel
I now wish to take you through our assessment of the options 17 16

13. LOBH DETR L5810 BH DfEE 318 DSS 050130 ONS 01BD Dept of Health English
0270
Forestry
Commission BH
ONS
01BD
English
Heritage
LOBH
RICHMOND UPON THAMES
Thank you Lionel
I now wish to take you through our assessment of the options 17 16

14. Output Areas (OAs) – why?
output separated from collection
consistent size in population/no of households
socially homogenous (based on tenure of household and accommodation type)
meets confidentiality thresholds
align with administrative boundaries
England and Wales, but consistent throughout UK

15. Output Areas – key features
approximately 175,000 OAs (England and Wales)
target of 125 households in each OA minimum 40 households or 100 people
size allows for a fine resolution of data analysis
boundaries made freely available for non-commercial purposes

16. Output Areas

17. A group of Output Areas

18. Lower Layer Super Output Area

19. Middle Layer Super Output Area

20. Geography policy for statistics
Emphasis on stability (“30 years”)
improving our ability to measure change over time
Use of standard geographic units
Statistics built from these blocks - or by estimation for other areas
Districts
Super OAs
Output Areas
Grid reference

21. Measuring population in E&W
Many national administrative registers but no comprehensive population register
Census the only exact count
Mid-year population estimates
Experimental data
from Census updated by administrative sources
Published for lower super output areas but internally modelled for postcodes

22. E&W Grid map
Direct aggregation permits production of 1km grid square estimates and generation of grid map
Postcodes allocated to each 1km grid square
Direct aggregation of postcode populations

23. E&W Grid map Create 1km grid using ETRS89
Select E&W by intersect with NUTS1 boundaries
Select populated/unpopulated grid squares
Spatial join to calculate population total for each grid square
Append the population totals back to the main grid file

24. E & W Grid Map – further work
Aggregation from small area estimates no disclosure issues from: may not be possible to use same method with 2011 census data
Challenge of GISCO grid for UK users: incompatible with GB National Grid and other mapping products
Simplistic aggregation – assumes all population of postcode falls in same grid cell: need to consider redistribution model, edge effects
Potential for modelling distribution at higher resolution within cells

25. E & W Grid Map – questions