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GPD Support

Deprivation

NHS National Services Scotland ISD Scotland & NHS National Services Scotland

The Scottish Index of Multiple Deprivation (SIMD)

The Scottish Index of Multiple Deprivation is the Scottish Government's official tool for identifying areas in Scotland concentrations of deprivation by incorporating several different aspects of deprivation (multiple-deprivations) and combining them into a single index. Concentrations of deprivation are identified in SIMD at Data Zone level and can be analysed using this small geographical unit. The use of data for such small areas helps to identify 'pockets' (or concentrations) of deprivation that may be missed in analyses based on larger areas such as council wards or local authorities. By identifying small areas where there are concentrations of multiple deprivation, the SIMD can be used to target policies and resources at the places with greatest need. The SIMD identifies deprived areas, not deprived individuals.

SIMD 2016

SIMD 2016 was based on the 2011 Data Zones and comprised seven domains (income, employment, education, housing, health, crime, and geographical access). The SIMD has the advantage of being a measure of multiple deprivation. A total of 38 indicators were used in the 2016 release, including indicators relating to geographical access to key services (travel times for driving and public transport) which are the best available indicators to measure difficulties in accessing local amenities as a problem specific to rural deprivation. SIMD 2016 was published on 31 August 2016.

For any particular SIMD release, each Data Zone is ranked according to the overall score from the range of indicators which put together creates the index. Ranks are grouped into cut-offs or categories such as vigintiles, decile, quintile and the three most deprived vigintiles or 15% most deprived Data Zones. SIMD 2016 is based on the 2011 Data Zones. Population-weighted ranks have been based on 2014 small area population estimates (uncorrected version).

Historical versions of SIMD (SIMD 2004, 2006, 2009 and 2012)

The SIMD is based on small areas called Data Zones. 2001 Data Zones were introduced in 2004 to replace postcode sectors as the key small area geography for Scotland. They were based on 2001 Census Output Areas and were intended to be a stable geography over time, with a reasonably consistent population size, and boundaries set to respect physical boundaries and natural communities as far as possible. Because they are population-based, Data Zones can vary hugely in size. For example, in towns and cities where people live close together, Data Zones can contain only a few streets, while in rural areas that are sparsely populated, they can cover many square miles. Scotland is divided into 6,505 Data Zones each containing around 350 households and mean population size of 800 people. For each Data Zone, a deprivation score is calculated from a large number of indicators in several domains, which is used to determine the ranking for each Data Zone from 1 (most deprived) to 6,505 (least deprived).

There have been SIMD releases in 2004, 2006, 2009 and 2012. Note that only the corrected 'version 2' for the 2009 release, referred to as SIMD 2009v2, is used.

The population has dropped to zero in the smallest Data Zones and increased to over 8,000 in the largest, due to movements of populations over time. The Scottish Government have redrawn Data Zone boundaries to take changes in population since the first edition into account and ensure a more consistent population size. The new redrawn Data Zones have been based on the 2011 Census, and are known as '2011 Data Zones'. They were released on 6th November 2014.

Lookup Files


Data Zone-SIMD lookup files

The GPD team create the below population weighted SIMD lookup files using:

  • Data Zone-SIMD lookup released by the Scottish Government (SG)
  • Population estimates from National Records of Scotland (NRS)
 
SIMD version Data Zone Version Format Size Format Size
SIMD 2016 Data Zone 2011 SPSS 1MB CSV 1MB
SIMD 2012 Data Zone 2001 SPSS 1MB CSV 1MB
SIMD 2009v2 Data Zone 2001 SPSS 1MB CSV 1MB
SIMD 2006 Data Zone 2001 SPSS 1MB CSV 1MB
SIMD 2004 Data Zone 2001 SPSS 1MB CSV
1MB

Last release: SIMD 2016 released by the SG in August 2016
Next release: is yet to be announced


Postcode-SIMD lookup files

The GPD team create the below population weighted SIMD lookup files using:

  • Data Zone-SIMD lookup released by the Scottish Government (SG)
  • Population estimates from National Records of Scotland (NRS)
  • Postcode to Data Zone mapping from NRS postcode extract
 
SIMD Version NRS Postcode Extract Version Format Size Format Size
All 2017_2 SPSS 187MB CSV 186MB
SIMD 2016 2017_2 SPSS 48MB CSV 39MB
SIMD 2012 2016_1 SPSS 71MB CSV 61MB
SIMD 2009v2 2012_2 SPSS 33MB CSV 28MB
SIMD 2006 2009_2 SPSS 32MB CSV 31MB
SIMD 2004 2006_2 SPSS 28MB CSV 26MB

Last update: SIMD 2016 updated with 2017_2 NRS postcode extract in September 2017
Next update: SIMD 2016 will be updated with 2018_1 NRS postcode extract in April 2018


Guidance on the use of SIMD

Please read the Guidance on the Use of SIMD Download PDF file [436kb] before using any SIMD files. This document includes advice on using SIMD, which version to use and how to attach the deprivation data to your data.

Please read the below notes.

Population Weighting

SG quintiles and deciles are constructed differently from ISD’s methodology (population weighted). The reason for ISD using population weighting can be found here: Why ISD use population weighting? Download PDF file [180Kb]

The Scottish Government (SG) publish SIMD deprivation categories which are NOT population weighted. The SG rank Data Zones from most to least deprived and then split this into:

  • 20 deprivation vigintiles with 5% of the Data Zones in each vigintile
  • 10 deprivation deciles with 10% of the Data Zones in each decile
  • 5 deprivation quintiles with 20% of the Data Zones in each quintile

ISD rank Data Zones from most to least deprived using the Scottish Government’s un-weighted SIMD and by using the National Records of Scotland population estimates, split this into:

  • 20 deprivation vigintiles with approximately 5% of the population in each vigintile
  • 10 deprivation deciles with approximately 10% of the population in each decile
  • 5 deprivation quintiles with approximately 20% of the population in each quintile

ISD analyses use population-weighted quintiles and deciles for both numerators and denominators in all the above files and in datamarts such as ACaDMe. The Scottish Government and National Records of Scotland analyses generally use the un-weighted deprivation categories.

It is important not to mix population-weighted deprivation categories with the un-weighted deprivation categories in the same analysis.

Ordering

For SIMD 2009v2, SIMD 2012, SIMD 2016 and future releases, ISD follows the SG convention for ordering quintiles and deciles 1 = MOST deprived; 5 or 10 = LEAST deprived.

PHI analyses based on SIMD 2006 or SIMD 2004 will be left in their current format:
1 = LEAST deprived; 5 or 10 = MOST deprived.

To avoid confusion, deprivation categories should always be fully labelled, e.g. for SIMD 2016, 'decile 1 (most deprived)'...'decile 10 (least deprived)'.

For time trend analyses combining SIMD 2004/2006 with SIMD 2009v2/2012/2016 please be aware of the reversing of the ordering of deprivation categories. Please ensure that the reversing is treated appropriately in analyses to ensure that the most and least deprived deprivation categories are not used the wrong way round.

Limitations of SIMD

The SIMD identifies deprived areas, not deprived individuals.

The SIMD cannot be used to determine 'how much' more deprived one Data Zone is than another e.g. it is not possible to say that Data Zone X, ranked 50, is twice as deprived as Data Zone Y, ranked 100. The SIMD can be used to identify Scotland's most deprived small areas on the overall index and each individual domain, commonly by applying a cut off such as 10%, 15% or 20%. The cut off should be informed by whether it aims to target areas with the very highest concentrations of deprivation or to be wider ranging. The SIMD provides a relative measure of deprivation which means that the main output from SIMD - the SIMD ranks - can be used to compare Data Zones by providing a relative ranking from most deprived (rank 1) to least deprived (rank 6,505).

One theoretical criticism of SIMD is that because it includes a health domain, its use to study deprivation patterns in health is invalid because the SIMD and the health indicator being studied are not independent of each other. However, the health domain is weighted to account for a relatively small part of the overall SIMD (14% of SIMD 2009, 2012 and 2016), and analyses of health inequalities using SIMD 2004 were found to give similar results whether the health domain was included or excluded, because that domain was so highly correlated with the overall index. Therefore, PHI advice to analysts is that the full SIMD may be used for analysing health data.

Further Information

Further information can be obtained on the Scottish Government's website Opens in new window.


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