Welcome to North Ayrshire Council


A very warm welcome to North Ayrshire Council who have recently joined the SASPAC scheme to take full advantage of the Scottish 2011 Census results being published in the coming months.


The latest output plans can be found in the NRS Prospectus, in summary the next releases scheduled are:

  • Release 2B (14 November) – Key Statistics and Quick Statistics tables for all 16 levels of census geography.
  • Release 2C (mid December) – Key and Quick Statistics tables related to Living Arrangements for all 16 levels of census geography.
  • Releases 3 & 4 (date tbc) – detailed Local Characteristics (LC) and Detailed Characteristics (DC) tables.

Finally, a reminder that we are running a SASPAC/Census training course in Motherwell on 27 and 28 November – please contact the helpdesk to book your place.

A warm welcome to Oxfordshire CC


We’d like to offer Oxfordshire County Council a warm welcome to the SASPAC software scheme.


With Census data coming thick and fast in the coming months, remember the SASPAC team provide training in both the Census data and how SASPAC can help you make the most of this huge dataset. Visit out training page for more info.

SASPAC Training dates


We’ve just published our next London (City Hall) training courses on our website, forthcoming dates are:

  • Wednesday 12 June
  • Tuesday 16 July
  • Tuesday 20 Aug
  • Tuesday 10 September

These introductory courses provide users with all the tools they need to begin extracting and using census data. It is also an excellent opportunity for those who have used SASPAC before, but need a refresher, to brush up on their skills. The materials have also been updated to incorporate the latest Detailed Characteristics Census tables published in May.

A copy of the training programme can be found here (.pdf). If you would like to attend, or have a colleague who would like to learn to use SASPAC, please contact Wil Tonkiss to book a place. All the course materials can be found on our training pages.

Training Videos


New training videos are now available for Modules 3a and 3b! These demonstrate how to select areas by text listing and using mapping through SASPAC.

SASPAC Training – Places Available


The next Introduction to SASPAC course is scheduled for Tuesday 21st May at City Hall, London.

If you would like to attend, or have a colleague who would like to learn to use SASPAC, please contact Wil Tonkiss to book a place.

The introductory programme will provide users with all the tools they need to begin extracting and using census data. It is also an excellent opportunity for those who have used SASPAC before, but need a refresher, to brush up on their skills.

Full details of the course content can be found here: One-day Course.

Website update: new FAQ & Video



To help support users we have recently added an FAQs page to our website – if you have any questions you’d like us to answer please send them through the helpdesk.

We’ve also added a number of software videos to support our training materials, which can be found here.

We will be updating these resources regularly and will notify you as and when new content goes live.

Creating Improved Census Ward Population Estimates


ONS’ GSS policy of best-fitting 2011 Census estimates (and other national statistics) from output areas has been causing issues for some local authorities that have seen ward boundary changes since 2003. SASPAC has received considerable interest from users on this particular issue as well as discussion on the StatsUserNet and Knowledge Hub forums.

The Issue

All 2011 Census ward estimates have been created using a method of best-fitting from the population weighted centroids of the underlying 2011 Census Output Area (OA). The population weighted centroid is a single point within the OA that represent the median location of households. The whole population of this OA is then assigned to the ward in which it falls. This means that where OA boundaries no longer match ward boundaries (i.e. they have changed since 2003 when the 2001 Census OAs were produced on an exact-fit to wards) the population/household estimates may not reflect all households physically located within the ward boundary. Conversely households outside the ward boundary may be included.


2011 best-fit of OAs to Wards: OA4 is allocated to WARD 2 because OA4’s population weighted centroid falls within the WARD 2 boundary (Source: ONS, An overview of best-fitting: Building 2011 Census Estimates from Output Areas)

Creating improved estimates

This is leading many organisations to look out how they can create improved best-fit estimates using alternative methods of redistributing the OA population more accurately. A number of methods can be used such as:

  • using the proportion of each OA’s areal extent that falls within each ward (assumes the population is evenly distributed across the OA) or,
  • using Census day address lists (e.g. Royal Mail Postcode Address File or the Local Land and Property Gazetteers maintained by local authorities) to distribute the population. Tees Valley Unlimited have very helpfully documented their approach here.  

Another approach will be possible when the 2011 Census Unit Postcode Headcount data (Postcode estimates tables are currently expected in May (p35 of the 2011 Census Prospectus (.pdf)) are published. These will provide details of the number of males, females and occupied households for each Census day postcode and will provide a very accurate method of redistributing the population to ward boundaries.

How SASPAC can help?

Once you have created the improved OA population distributions, SASPAC’s rezoning tool can then be used to easily recreate all the Census tables for these more accurate ward household or population distributions. For more information in how to rezone in SASPAC see Module 4 of our training manual.

Census estimates for other areas such as Parishes have also been best-fitted from whole OAs. This re-estimation method can be applied to any zones where best-fitted figures are insufficiently precise.

But remember…

Creating your own local ward estimates will produce alternative figures to those officially produced by ONS and should be documented and correctly labelled as such to avoid any confusion. Also, the best-fit methodology will be applied to create other ONS datasets, so care should be taken to use denominators created using the best-fit method.

Some useful resources:

ONS page on exact and best-fit estimates

ONS overview of the best-fitting methodology

Download median population weighted centroids for output areas, super output areas and workplace zones in shp and mid/mif format.

ONS National Postcode Directory

ONS 2001/2011 Census geography lookups products