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

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!)

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

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

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

Avon 1995 19

19

Yorkshire and Humberside 19

Yorkshire and Humber 19

Yorkshire and the Humber 19

Yorkshire and The Humber 19

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

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

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

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

Output Areas

A group of Output Areas

Lower Layer Super Output Area

Middle Layer Super Output Area

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

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

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

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

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

E & W Grid Map – questions