Small area data has lots of potential uses, writes Dr Nissa Finney; by healthcare or education providers to tailor their services, by the local authority in forecasting, or for academic research. But under money-saving proposals currently being considered, the Census as we know it – and the subsequent availability of these data – may disappear.

Statistical and small area boundaries are invisible on the ground. Yet they shape the physical nature of cities because they demarcate areas that are governed. And they are part of the construction of places because they determine a space that has political representation, or is served by a care trust, or is provided with services by a particular local authority.

Statistical boundaries are ‘territorial units’ within the UK for which data are collected and collated by the national statistical agencies. There are many types of sub-national boundaries for which small area data are produced – administrative, electoral, census, health, postal. And the boundaries within each of these types change frequently.

For example, census boundaries change in an attempt to provide statistics that reflect geographical areas with some social meaning and amendments to electoral boundaries may reflect demographic change. Statistical boundaries both shape and reflect society.

In the UK, statistics are produced for very small areas. For example, census data are published for ‘Output Areas’. Output Areas have a recommended size of 125 households and are generated from data after the completion of each census.

Output Areas are designed to have similar population sizes to each other and to be as socially homogenous as possible based on tenure of household and dwelling type. They are small enough to sit within larger boundaries and always fit exactly within local authority districts.

What kind of data can we get for these small areas? Good examples are provided by the Neighbourhood Statistics website, the portal through which Office for National Statistics (ONS) disseminates its small area data.

By selecting the area you’re interested in, you can view hundreds of data tables on all kinds of topics drawn from census and other data that ONS manages. You can find out about population, education, health, work, deprivation and more for small areas.

How might this type of data for small areas be used? Perhaps it is used by providers of health care or education in Manchester to tailor their services for their population. Perhaps it is used by the University to monitor how well it is engaging with the community within which it sits. Perhaps it is used by the local authority in population and economic forecasts. It is certainly used by academics interested in population change.

For example, census data for small areas have been used in Dynamics of Diversity: Evidence from the 2011 Census briefings produced by the ESRC Centre on Dynamics of Ethnicity (CoDE) in association with the Joseph Rowntree Foundation. These analyses of census small area data have revealed increases in ethnic mixing.

Now is an important time to think about how these small area data are used. That is because they are under threat. The ONS is currently assessing alternatives to a census for producing population and small area socio-demographic statistics for England and Wales.

The review programme is called ‘Beyond 2011’. The impetus comes from the Treasury and the Select Committee report ‘Counting the Population’ from May 2008 and the UK Statistics Authority, which would like to see feasible and less costly alternatives to the census that will make the 2011 Census the last of its kind.

This call to find a less costly alternative to the decennial census came prior to the 2011 census, which has been widely acclaimed as the most successful in recent times; efficiently run, cost-effective and producing a breadth and depth of data that is world-leading.

The ONS is currently running a public consultation on its Beyond 2011 proposals (closing 13 December) and will put its recommendations to government in 2014.

The proposed changes may mean that small area data are not produced, and it is a real possibility that the future data landscape in the UK will not include the world-leading breadth and quality of small area data that we currently enjoy.

If small area data are to be included in the Beyond 2011 recommendations, the case for them needs to be made. There is a danger they will be lost because they’re taken for granted; because they are used by many, but their origins and the efforts to produce them, and their world-leading quality are not necessarily recognised.

It is with this concern in mind that interested parties should consider the appeal by the Beyond 2011 Independent Working Group to provide examples of how you have used Census statistics, particularly for small areas (local authority level and below).

These can be sent to ONS at benefits.realisation@ons.gsi.gov.uk and copied to the Independent Working Group at AreaStatistics@gmail.com. You may also want to respond to the ONS consultation, due later this Autumn.

Perhaps it is helpful to think about this is terms of what we won’t have, and what we won’t be able to do, if we don’t have small area data.

If small area statistical boundaries and the information about population, health, housing, education, work, migration that they contain were not to exist, what would we not know about cities, and about how cities are changing?

How would our understandings of contemporary cities be different without the backdrop of the world-leading quality small area data that we currently enjoy?

• This is an abridged version of a blog post that originally appeared on the Cities@Manchester blog site.