Note on Data

The data in the UK Index of Systemic Trends is drawn from a variety of government and NGO databases. In all cases, efforts were made to obtain the most up-to-date information. However, in some cases (especially for the country comparisons) the latest available data may be from different years.

In most cases we have retained the definitions and terminology from the original data sources – including, most importantly, the use of “United Kingdom.” That is an artefact of the organisation of the data, and should not be read as support for the current constitutional positions of Scotland, Wales, or Northern Ireland.

Price deflators

Unless specified otherwise, UK data charts in this Index which display monetary values (such as average household incomes, average individual earnings and productivity measured as output per worker or output per hour worker) are uprated to the latest year in each chart using price deflators. Three different indices are used:

  1. For statistics relating to household incomes (such as incomes, earnings and the value of welfare benefits) where the time series begins in 1988 or later, the Consumer Price Index (CPI) is used.

  2. For income-related statistics where the time series begins before 1988, the Retail Price Index (RPI) is used.

  3. For productivity, the GDP deflator is used.

 For most of the period covered here (up until 2010) the RPI served as the UK’s primary measure of inflation. From 2010 onwards, however, the CPI became the official benchmark, aligning the UK more closely with international standards, particularly those used in the US and across Europe. Despite this shift, RPI continues to be published and remains relevant for certain contracts and historical comparisons. The UK Office for National Statistics only publishes detailed CPI data back to 1988 (although an imputed summary CPI measure is available back to 1955). Therefore, we have chosen to use the RPI for longer-run time series charts in this Index publication, with CPI used for short-run charts.

Inflation using the RPI measure is slightly higher in most years than the CPI or the alternative CPI(H) measure (a version of the CPI which includes housing costs in the index).