IMD Methodology
The purpose of this section is to provide a broad overview of the methodology used to construct the four separate Indices of Deprivation. Those wishing to access more detailed information should follow the links to the Indices' technical reports shown in the 'Useful links' section.
The methodologies used to derive the separate indices of multiple deprivation are broadly similar. In each case, the index measures the level of multiple deprivation experienced by individuals in small areas. Firstly, levels of deprivation are measured for a number of separate dimensions or 'domains'. The number and title of domains varies between each index but each measures deprivation across key themes of income, employment, education and health.
For each domain, deprivation is calculated according to a series of summary statistics or 'indicators'. These indicators are designed to measure key features of a particular deprivation theme. The choice of indicators is agreed through consultation and varies between each index. Typically there are between two and six indicators per domain.
For each index, the indicators are combined in broadly the same way to provide a domain level measure of deprivation. Where possible and most notably in the income and employment domains, indicators are summed and divided by the 'at risk population' (for example, the number of income support claimants as a proportion of the total population) to give an overall area rate of deprivation. Where rates are not possible, appropriate weights for combining indicators into a single deprivation score are selected using a range of techniques including Maximum Likelihood factor analysis.
The domain level scores which represent specific dimensions of deprivation are then ranked and transformed to an exponential distribution. Weights are then applied to provide the overall Index of Multiple Deprivation for each country in the UK. The weights are selected according to a number of criteria which are used to assess the level of importance attached to each domain theme in the overall measurement of deprivation. As each index uses different indicators and domains, the weights applied to aggregate domain scores are different.
