Set ddata:Consumer price inflation time series

Important notes and usage information

Time series data gives access to a comprehensive database of time series from major national statistics and social economic releases.

From this month we will be publishing the main factors contributing to the differences between the unrounded inflation rates for the CPIH and the RPI. These differences are broken down into: mortgage interest payments, other housing components excluded from the CPIH, imputed rents (included in CPIH and excluded from RPI), other differences in the coverage of goods and services, and the formula effect. The final column titled "other differences including weights" is derived as a residual. These series are published as Table 5a in the consumer price inflation dataset while the corresponding figures for the Consumer Prices Index (CPI) can be found in Table 5b.

For the September 2018 publication (published 17 October 2018), we have reviewed and improved the published differences between the unrounded inflation rates for the CPI and the RPI – published as Table 5b in the consumer price inflation dataset. These minor revisions (of between plus and minus 0.02 percentage points) do not impact the headline measures of inflation and their components, but the supplementary statistics designed to provide users with further information on the differences between CPI and RPI.

Furthermore, the supplementary analysis aggregate differences are not impacted and only the components are. This is due to the household services maintenance policy item, introduced in 2010, being reclassified so that it is no longer treated as part of the "other housing components excluded from the CPI" aggregate. As a result, the "total housing components excluded from CPI", the "other housing components excluded from CPI" and the "other differences in coverage of goods and services" series have been recalculated from 2010 onwards. The headline difference is unaffected by this change.

While investigating the classification of these series, we identified an isolated one-off issue, which resulted in a minor error (of positive 0.01 percentage points) to the published value for "other differences including weights" in September 2012. This issue is separate to the reclassification outlined in this section and has no impact on the headline series, or any other series or data point.

Full historic series for each of the re-referenced indices are now available for users to view or download.

Regular re-referencing of indices is methodological good practice as it avoids rounding issues that can arise from small index values.

Please note that re-referencing does not impact on published inflation rates, although when using the indices to calculate to calculate inflation rates, it is important to use indices that are calculated in the same reference year. Re-referencing does not impact on RPI.