European Forum for Geostatistics Krakow October 2014 Ian Coady Geography Policy and Research Manager Office for National Statistics Why are we different No use of grids at the national or subnational ID: 633437
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Slide1
The complexities of publishing gridded data for the UK
European Forum for GeostatisticsKrakow – October 2014
Ian
Coady
Geography Policy and Research Manager
Office for National StatisticsSlide2Slide3
Why are we different?
No use of grids at the national or sub-national levelNo use of administrative data in the collection and publication of statistics
Historic reliance on administrative boundaries for the publication of official statistics
Large user demand for Census
microdata
on administrative boundariesSlide4
But….
It is (partially) understood that the publication of Census microdata at the administrative level is not sustainable due to disclosure issues
INSPIRE has given us a common platform and specification for the publication of statistics
…and I am here to try promote the interoperability of data at the European levelSlide5
Output Areas
Created for the 2001 Census
Built around consistent numbers of population and households
Used postcodes as the building blocks
Included a high level of social homogeneity
Some cartographic constraints were usedSlide6Slide7
Geography Policy for National StatisticsSlide8
Previous work on grids
1km grids provided between 2005 and 2006Provided by aggregating population estimates from the postcode level to the grids
Lack of administrative data sources meant data below postcode level was no longer available
ONS has provided data for England and Wales but (we think) Scotland and Northern Ireland have provided data separatelySlide9
Best-Fitting from PostcodeSlide10Slide11Slide12
Research Questions
1) How can the sex and age variables that do not currently exist on the postcode level mid-year population estimates be published?
2
) How do the methodologies for publishing gridded population data differ across the devolved administrations of the UK, and how could this approach be harmonised?
3
) What is the statistical impact of publishing gridded data at the postcode aggregate level rather than from the
microdata
?
4
) What options exist for visualising gridded population data?Slide13
Small Area Population Estimates team no longer produce mid-year estimates at the postcode level
To align with the Geography Policy for National Statistics all estimates are now produced at the Output Area levelSlide14
Best-Fitting from Output AreasSlide15Slide16Slide17Slide18Slide19
Exact-Fitting from Census MicrodataSlide20Slide21Slide22Slide23
Grid Methodologies
Level
Records
Frequency
Source
Additional Variables
Households
23,406,162
10 years
Census
Yes
Postcodes
Unknown
Unknown
No
Output
Areas
181,408
Annual
Mid-Year Estimates
NoSlide24
Other alternatives…..
Use soil sealing layer (SSL) to produce
dasymetric
reallocation of population:
Small
area population data are intersected with the SSL and used to re-weight population counts into settled areas, which are then aggregated to grid
cells
May
offer consistency with broader European practice, but inconsistent with other ONS approaches.
Disclosure
control attitude unknown and would need to be tested.
Offers alternative
to
postcode use
that
can
no longer be carried out.
Use
ONS built-up areas
layer
to produce
dasymetric
reallocation of population
:
Variant
of
previous option
but consistent with ONS data
sources as uses the
Built-Up Areas (BUA) layer instead of SSL.
Intersects
OA boundaries
with
BUAs and
allocates
population
to
BUAs in proportion to area. Then aggregate to grid cells.
Uses
only published ONS data, so no additional disclosure risk.
Reproducible
methodology
but
needs to be tested
.Slide25
A country of countries
Northern Ireland have disclosure concerns about the disclosure risk of publishing on both the Irish National Grid and the GEOSTAT Grid
Both Scottish and Northern Irish Census
microdata
is stored separately and experience shows accessing this data can be a long and slow processSlide26
Sustainable variables
Small Area population estimates do not currently include sex or ageIncreasing use of administrative data could allow this to be included
Change to the SAPE processes would be required
Would depend on the agreed level of publication but could potentially go further than age and sexSlide27
Conclusions
Producing UK level grid outputs is possibleProducing them from Census microdata
is possible but only through Census and the differences between this and the small area population estimates would be
noticable
Differences in the methodologies of the devolved administrations are superficial but improved data sharing is needed to do this on an ongoing basis
Additional variables could be provided on an ongoing basis but only through administrative data that has not yet been integrated into the ONS Statistical Business Process ModelSlide28
Any questions???