SIMD - Frequently Asked Questions

If you have a small number of postcodes, you can find the SIMD rank by putting one postcode at a time in to the 'Quick Profile' tool on the Scottish Neighbourhood Statistics website. SIMD rank is one of the summary statistics provided in the profile.

If you have a large number of postcodes, you need two separate files:

A postcode lookup file is included in the geography download product from Scottish Neighbourhood Statistics. The lookup is a list of all postcodes in Scotland, and the data zone in which it is situated, along with various other geographies such as intermediate geography or health board. The geography download is available from the data download section of the SNS website. The file in the download that contains the postcode index is prefixed 'snspc…'. Note that the file is in a comma separated format as it is too large to load in to excel. To use the file, load it into SAS, Access, or split the file up using notepad so that you can then open in excel.
A data zone to SIMD lookup is available from the 'background data' section of the SIMD website. There are two sets of files - one for SIMD 2004 and one for SIMD 2006. There is a series of spreadsheets relating to each of the SIMD domains. The most relevant file for this is spreadsheet part 2. Within this spreadsheet there is a list of all 6,505 data zones and, for each one, the overall SIMD rank and the ranks for each of the SIMD domains are provided, along with populations and local authority.

To use the files you need to attach the data zone code to your list of postcodes using the first lookup, and then attach the SIMD rank to those data zones using the second lookup.

If you want to use SIMD deciles/quintiles etc, there is an additional lookup that you can use. In the SIMD background data section, annex B contain a lookup from rank to decile/quintile/percentile etc.

Can I produce an average SIMD rank for areas larger than data zones?

How do I compare areas that are larger than data zones?

Can I rank local authorities/ larger geographies in terms of multiple deprivation?

Because the SIMD scores and ranks are a relative measure of deprivation, they can not be averaged. For example, a data zone ranked 5 is not necessarily twice as deprived as one that is ranked 10, so it is not appropriate to average ranks.

The SIMD is calculated at the data zone level only. In order to measure how deprived larger areas are, it is necessary to look at the proportion of data zones within that larger area that fall within the 5, 10 or 15% most deprived areas or the proportion that fall within deciles or quintiles.

To compare local authorities, it is most appropriate to use the proportion of data zones, or the proportion of the population, in the 15% most deprived. Examples of this kind of analysis can be found in the SIMD 2006 General Report or in the statistical compendium.

It is important to bear in mind that data zones nest directly into intermediate geographies and local authorities, however, they do not fit exactly into other higher geographies e.g. wards. Any comparisons of the SIMD at these geographies will be on a 'best fit' basis only.

What do movements in ranks between years mean?

How can we use SIMD to understand communities better?

How do you produce analysis over time? Can you only use the most recent index?

How much change is absolute and how much is relative? How do we know for individual data zones?

The SIMD ranks provide a relative measure of deprivation. It is important to note that because the rankings of data zones within the index are relative, it is not possible to tell, from the rank, how much more deprived one data zone is than another. A data zone ranked 5 is not necessarily twice as deprived as one that is ranked 10. Likewise, a data zone with a more deprived rank in SIMD 2006 than it had in SIMD 2004 may not necessarily have become more deprived in absolute terms, rather its relative position to other areas has worsened.

To find out why an area has a different ranking to another, it is possible to investigate the domains and indicators that make up the overall SIMD rank. These are available in the background data section of the SIMD website. Individual indicators provide absolute values for each data zones and so can provide information on how much more deprived one area is than another.

To assess why a data may have changed rank over time, again, it is possible to look at individual indicators in the background data section of the website. Care must be taken when comparing indicators from SIMD 2004 and SIMD 2006 as some data sources have changed and the methodology for compiling the indicators may have changed. These changes are described for each indicator in the SIMD 2006 technical report.

The employment domain, however, has seen no changes to methodology or data source between the two Indices and, as it is an absolute measure (proportion of working age population that are employment deprived) and it has one of the greatest weightings in the overall SIMD rank, it will provide a good indication as to why an area may have changed rank.

Finally, as data zone boundaries have remained constant, populations within data zones may have changed and this might affect the overall SIMD rank. It is, therefore, always worth noting whether there have been substantial population changes in your data zone of interest. Population change for data zones that have moved in to or out from the 15% most deprived can be found in tables 1.7 and 1.8 of the statistical compendium and total populations for all data zones can be found in the background data (spreadsheet part 2).

More detailed population information and thousands of other indicators are also available from the Scottish Neighbourhood Statistics website and can be used to assess and illustrate differences between data zones and change over time.

Is there a UKwide map of deprivation?

It is not possible to produce a UK wide index of deprivation, although each of the four nations in the UK produces its own index. Although each of the four indices are based on the same methodology, they are not strictly comparable for various reasons, the two main reasons. Firstly, the indices use different geographies (Scottish data zones are considerably smaller than the SOAs used in England and Wales) so it is not possible to compare like-for-like. Secondly, due to data availability, each index uses slightly different indicators and weightings.

The Office for National Statistics have put together a website to explain in more detail the similarities and differences between the four indices.

Is the population in the 15% most deprived data zones 15% of the population ofScotland ?

Yes, because the data zones have roughly the same population, the population in the 15% most deprived areas is approximately 15% of the Scottish population, although this is subject to change as the populations of data zones will change over time.

Can you rank data zones by individual SIMD domains?

Yes, each domain can be used in its own right to investigate specific aspects of multiple deprivation. The background data on the SIMD website provides ranks for all of the domains at data zone level. It is also possible to look at interactive local authority maps for the individual domains using the interactive mapping website.

Deciles (tenths) and vigintiles (twentieths) are also available for each domain on the SNS website.

SIMD Methodology

Does the SIMD take account of the age and sex structure of the data zone population?

Yes, to a certain extent. Each indicator has a population denominator and this is not always the total population. For example, the employment domain denominator is the working age population and the secondary attainment rate uses the population of S4 pupils only.

For some of the indictors (mainly health indicators) the rates have been indirectly age-sex standardised - this means that the rate you see at data zone level is the ratio of what you expect to what is observed, given the age and sex structure of the population in that data zone. If the rate is greater than 100, the value is greater than you might expect and if it is lower than 100, it is less than you might expect, based on the national average. The SIMD 2006 technical report provides more information on the denominators used for each indicator and the process of age-sex standardising.

How were the domain weightings decided?

Why isn't there an equal weight for all the factors in the index?

The weights are those used in Scottish Indices of Deprivation (SID) 2003, adjusted to allow the inclusion of the Housing domain in SIMD 2004 and Crime domain in SIMD 2006. The work by Oxford University's Social Disadvantage Research Centre on SID 2003 concluded that the Current Income and Employment domains should carry most weight in the overall index. This is partly due to the fact that these domains are more robust and partly since this is in line with the academic literature on deprivation. The weights for the remaining domains were chosen with the criteria that the domains with the most robust indicators should be given the greatest weights. (It is important to note that only indicators, which are sufficiently robust, are included within the Index.)

The weights for SID 2003 were strongly based on academic literature and Oxford University's own research. In particular, they pointed to Townsend's definition of deprivation: 'while people experiencing some forms of deprivation may not all have low income, people experiencing multiple or single but very severe forms of deprivation are in almost every instance likely to have very little income and little or no other resources.' They therefore accorded the Income and Employment domains the highest weights since they saw worklessness as a deprivation in its own right, and not simply a driver for low income.

The choice of weights is a matter of informed judgement. In the final analysis there is no ultimate method by which to measure multiple deprivation, as it is a combination of individual deprivations, measured here in the Index domains. However, the domain weights in SIMD 2004 and SIMD 2006 have been chosen based on those used in SID 2003 which gave due regard to the driving forces behind multiple deprivation, as discussed in the wider academic literature. (More information in criteria section above).

All decisions on weightings take place after a sensitivity analysis of the effects of changing the weights and consultation with the ScotStat Measuring Deprivation Advisory Group.

Has the methodology you use been independently reviewed?

Yes. The University of Glasgow's Robertson Centre for Biostatistics conducted an independent evaluation of the methodology used in the SIMD 2004. They passed the 'health check' on its methodology, however, they did produce a series of recommendations to simplify and improve it. The Scottish Government accepted some of these recommendations. The full report by Glasgow University and the Scottish Government's response were published in November 2005 and can be found in the publications section of the SIMD website.

What input did Ministers have in putting together the index?

Decisions on the methodology used in the SIMD are made by Government Statisticians in conjunction with the ScotStat Measuring Deprivation Advisory Group. In 2006, the UK's National Statistician approved the SIMD as a National Statistics product, which means that decisions on methodology, choice of indicators and timing of the index are free from political intervention.

What is the update timetable for the index? Will it be every two years?

The next index is due to be published in the late 2009. This will bring the index back in to sync with the Spending Review and allow time to develop indicators. There is currently no commitment to update every two years. It is expected that decisions on timings of updates post 2009 will be made when the 2009 index is published.

The Scottish Government

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Using the SIMD

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