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Home » Other Data » Population data used in calculations

11/24/2009 11:12:59 AM

jdallen
jdallen
Posts: 8
Hello All,

I had a question about the population data that Accession users use for accessibility calculations. Whilst I note that there is a lot of census/population information available on the neighbourhood statistics website, my question concerns the level of detail of population data typically used in Accession calculations. I am particularly interested in some of the data that might have been used for accessibility calculations related to job seekers allowance claimants and pupils in receipt of free school meals.

Information appears to be available down to Mid and Lower Super Output Area levels from the neighbourhood statistics website for these data sets – however not at Output Area level. I was assuming that Accession calculations incorporating population data should ideally use data at the Output Area level (i.e. approx 200-500 pop), to give more meaningful output. I also note that whilst some population information estimates are released by ONS to update from the 2001 census, these are not released at the Output Area level (I’m assuming because it is not possible to be that accurate with population update estimates). I was interested to hear what levels of population detail other Accession users use/have used for their accessibility calculations, particularly for example for Accessibility Strategy work for LTP2, or any other thoughts around this issue.

I appreciate any thoughts or advice that others might be able to share,
Many thanks,

Jamie
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1/12/2010 9:23:34 AM

jdallen
jdallen
Posts: 8
Hello All,

I just wondered whether anyone had any thoughts on my original post below? Basically this relates to the size of population data that Accession users typically use in calculations.

I had previously assumed that in undertaking calculations in Accession, population data down to Output Area level (i.e. 200-500 pop) should ideally be used to give more meaningful outputs, but I note that a lot of data typically used in calculations for previous LTP2 Accessibility Strategy work typically uses data at Lower Super Output Area levels (i.e. 1000-2000 pop). I just wondered what Accession users thoughts were on the levels of population data used in calculations?

Any thoughts or comments on this would be much appreciated,

Many thanks,

Jamie
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1/12/2010 5:08:30 PM

keithdrew76
keithdrew76
Posts: 60
Jamie
I think the answer to the population question realtes to the size of your study area and the study purpose, as well as the resolution of data supply. If you doing a very local study then using population datasets at higher resoultion (above OA) is probably not a good thing. However if you are doing a strategic assessment (such as LTP2) then using data at SOA level is probably not so much of an issue, for example (an LTP2 assessment I undertook) measured access from SOA to SOA for employment opportunity and overlaid areas of highest umemployment (at SOA level).
For employment data you may find more up to date data on NOMISWEB better, for school children (dpeendent on who you work for) you could form a partnership with the Education department and get hold of their data - although never easy with the DPA.

My method of measuring accessibility by general population is to use OS AddressPoint (households) and its up to date (dependent on your data supply). Only 1 more year till the Census of 2011, and 3 years till publication...

Note sure that helps, but willing to discuss more...

Cheers
Keith
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1/15/2010 12:31:17 PM

jdallen
jdallen
Posts: 8
Thanks Keith for your thoughts and for your information on alternative potential data sources. I agree it seems important to be considering the scale of the study area for the calculation. I guess it is always sensible to interpret the population calculation results with some caution bearing in mind some of the data assumptions that feed into the calculations. I work for West Sussex County Council, but was not here at the time when our LTP2 Accessibility Strategy was prepared, and the colleagues that were involved in the Accession work have moved on, so it is useful to get your thoughts and see the other comments on the forum. Using Address Point information for origin points is something that I have considered but have not tried yet, so I will consider this in future.

Thanks again for your thoughts,
Kind regards,

Jamie
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