Should boundaries be tied to the real world?

Posted by Nick Stripe on January 12th 2007

The consultation asks whether OA boundaries should be neatened to real world features.  This could be achieved by snapping them to, for example, OS MasterMap.

OA boundaries are largely abstract.  They were built up from artificial Thiessen polygons drawn around 2001 Census addresses.  As a result they cut across all other real world features, as do SOA boundaries further up the hierarchy.

Justin Martin picked up on this earlier in the blog and posted a comment.  He's keen to see a more coherent hierarchy of geographies down to individual features (or TOIDS).  There's clearly a potential data licensing issue here, but is this something worth investigating further?  What might the benefits be?

It's worth clarifying that any such neatening of the boundaries would not allow addresses and households to shift between OAs.  There would be limits, therefore, to what could be achieved.  Clearly if geographies were to be redrawn from scratch then there would be a much wider debate to have.  This is covered fully in the consultation paper, the survey, and in my earlier "Stick or twist" post.

Other comments received so far have stated that the boundaries should be left alone.  That OAs are simply meant to group populations.  They are data containers and there is no need to make them fit physical features.  Is this a view that resonates with you?

Physical boundaries

Posted by Greg Ball (not verified) on 13/02/2007 - 17:50

There may be a problem in 2011 with the abstract nature of the COA boundaries - abstract shapes containing collections of postcodes in 2001. At the moment boundaries across undeveloped areas often seem very arbitray. The effect on the 2001 results are not so great as these areas contain no records. However, I assume that in 2011 a new address will be allocated to a COA on the basis of its precise geographical location: a precise address being allocated by reference to an arbitrary line.This may lead to new housing being joined to an inappropriate COA.There may be a case for tidying some boundaries before 2011, particularly where it is known that development has or will occur.

SOA Boundaries

Posted by Roy Beiley (not verified) on 30/01/2007 - 09:56

I think it is time to call a halt to continually reviewing whether we have right sort of geography otherwise it makes it impossible to get a valid time-series on which to review trends - crucial to those like us in Great Yarmouth who are trying to measure achievement against Floor Targets for the purposes of Neighbourhood Renewal Fund.


Ideally, neighbourhood statistics should available for "neighbourhoods" which are recognised by local communities but Lower Layer SOA areas do approximate to these closely enough to be able to measure change over time.


What I would like is for more pressure to be put on agencies to produce their data at LLSOA level instead of Wards as we we were originally led to believe would be the case when NeSS were introduced!


So please stop moving the goalposts and deliver on what was promised!

Pinpointing problems using LSOA/OA geographies

Posted by James Cooper (not verified) on 26/01/2007 - 13:44

Hello,

This isn't a particularly technical reply but I'm not too concerned that OA/LSOA boundaries don't match street blocks exactly; although I am relatively pleased with the level of fit they seem to show with large features such as major roads and areas of open space.

I work for a district local authority and we are currently using LSOA level data to evaluate criminal and environmental problems across our Borough and inform the location of community safety environmental projects.

We chose LSOAs as our basic assessment unit because of the availability of IMD data as an initial filter (from 18 LSOAs to 9) and our need to manually aggregate our own environmental complaints/requests for service data at some level above street.

We don't have enough money to improve an entire LSOA however so in order to determine which block / street gets the money officers involved in the project have blended quantitative data with insights gained from site assessment and consultation.

When for example a street was considered high need with good opportunities for improvement and fell just outside of the selected LSOA boundary we have used a rule of thumb and included it in the scheme.

For us a future use of OAs when we get our all singing environmental gazetteer on line would be as containers for complaints data allowing us to express them as rates and prioritise works. A strong linkage to postcodes and street block might be an advantage for this purpose but I still think that in terms of public policy and action the quantitative picture can only narrow the lens so far before specific assessment of an area and the individuals within it becomes vital.

Apologies for the length of this reply!

Oh, and what on earth is a TOID(S)?

TOIDs

Posted by Nick Stripe on 26/01/2007 - 17:01

Thanks for your comments James. No need to apologise! The following links help to explain TOIDs - essentially a unique OS reference number for all features in the country (there's about 400 Million of them I think).

http://www.ordnancesurvey.co.uk/oswebsite/business/sectors/transport/understanding/toids.html

http://www.guardian.co.uk/uk_news/story/0,3604,1164335,00.html

Toids

Posted by Paul (not verified) on 29/01/2007 - 09:23

This may be a more useful link for 'Toids' -
http://en.wikipedia.org/wiki/TOID