The index was developed by Vera Carstairs and Russell Morris, and published in 1991 as Deprivation and Health in Scotland. The work focusses on Scotland, and was an alternative to the Townsend Index of deprivation to avoid the use of households as denominators.  The Carstairs index is based on four Census variables: low social class, lack of car ownership, overcrowding and male unemployment and the overall index reflects the material deprivation of an area, in relation to the rest of Scotland. Carstairs indices are calculated at the postcode sector level, with average population sizes of approximately 5,000 persons. The indices are typically ordered from lowest to highest, and grouped into population quintiles. In the 1981, 1991 and 2001 indices, quintile 1 represented the least deprived areas, and quintile 5, represented the most deprived. In 2011, the order was reversed, in line with the ordering of the Scottish Index of Multiple Deprivation.  The low social class component of the 1981 and 1991 Carstairs index was created using the Registrar General's Social Class (later Social Class for Occupation). In 2001, this was superseded by the National Statistics Socio-economic Classification (NS-SEC). This meant that the definition of low social class had to be amended to reflect the approximate operational categories.  The definition of overcrowding was amended between 1981 and 1991, due to the inclusion of kitchens of at least 2 metres wide into the room count in the Census. 
The index was developed by Vera Carstairs and Russell Morris, and published in 1991 as Deprivation and Health in Scotland. The work focusses on Scotland, and was an alternative to the Townsend Index of deprivation to avoid the use of households as denominators. Elliott P, Cuzick J, English D, Stern R. Geographical and Environmental Epidemiology. Methods for Small-Area Studies. Oxford University Press. New York, 1997 The Carstairs index is based on four Census variables: low social class, lack of car ownership, overcrowding and male unemployment and the overall index reflects the material deprivation of an area, in relation to the rest of Scotland. Carstairs indices are calculated at the postcode sector level, with average population sizes of approximately 5,000 persons. The indices are typically ordered from lowest to highest, and grouped into population quintiles. In the 1981, 1991 and 2001 indices, quintile 1 represented the least deprived areas, and quintile 5, represented the most deprived. In 2011, the order was reversed, in line with the ordering of the Scottish Index of Multiple Deprivation. Brown, D., Allik, M. , Dundas, R. and Leyland, A. H. (2014) Carstairs Scores for Scottish Postcode Sectors, Datazones and Output Areas from the 2011 Census. Technical Report. MRC/CSO Social and Public Health Sciences Unit, University of Glasgow, Glasgow. URL The low social class component of the 1981 and 1991 Carstairs index was created using the Registrar General's Social Class (later Social Class for Occupation). In 2001, this was superseded by the National Statistics Socio-economic Classification (NS-SEC). This meant that the definition of low social class had to be amended to reflect the approximate operational categories. McLoone, P. (2004) Carstairs scores for Scottish Postcode sectors from the 2001 Census. MRC/CSO Social and Public Health Sciences Unit, University of Glasgow The definition of overcrowding was amended between 1981 and 1991, due to the inclusion of kitchens of at least 2 metres wide into the room count in the Census. McLoone, P. (1994) Carstairs Scores for Scottish Postcode Sectors from the 1991 Census. Public Health Research Unit, University of Glasgow URL
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Elliott P, Cuzick J, English D, Stern R. Geographical and Environmental Epidemiology. Methods for Small-Area Studies. Oxford University Press. New York, 1997
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Brown, D., Allik, M. , Dundas, R. and Leyland, A. H. (2014) Carstairs Scores for Scottish Postcode Sectors, Datazones and Output Areas from the 2011 Census. Technical Report. MRC/CSO Social and Public Health Sciences Unit, University of Glasgow, Glasgow. URL
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McLoone, P. (2004) Carstairs scores for Scottish Postcode sectors from the 2001 Census. MRC/CSO Social and Public Health Sciences Unit, University of Glasgow
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McLoone, P. (1994) Carstairs Scores for Scottish Postcode Sectors from the 1991 Census. Public Health Research Unit, University of Glasgow URL