13 August 2019
Error in the RPI
An error has been identified in the Retail Prices Index (RPI) in 2019, caused by an issue with the 2017 to 2018 Living Costs and Food Survey (LCF) dataset, which is used to produce the weights underpinning the RPI.
Indicative estimates show that if the corrected LCF dataset had been used to calculate the 2019 RPI weights, it would have led to an upward revision of 0.1 percentage points to the published RPI annual growth rate in March 2019, from 2.4% as currently published to 2.5% and a downward revision of 0.1 percentage points to the June 2019 rate, from 2.9% as currently published to 2.8%. No other month’s annual growth rates have been affected.
Using the corrected LCF data would also have led to an upward move of 0.1 index points to the March 2019 RPI, from 285.1 to 285.2, and a downward move of 0.1 index points in each of April (288.2 to 288.1), May (289.2 to 289.1) and June (289.6 to 289.5). As stated previously, these index changes would have only affected the annual growth rate for March and June 2019.
In line with the published revisions policy for consumer price inflation statistics, the RPI will not be revised. This error has been corrected from the July publication, which will be published on Wednesday 14 August. The growth rates and index levels will be published as usual using the corrected weights. However, users should note that as previous months’ publications will be on the previous basis, there will be a discontinuity between July’s and June’s index levels.
We are aware RPI is used in certain financial contracts and so we are publishing this notice outside of trading hours.
There is no impact on the Consumer Prices Index including owner occupiers’ housing costs (CPIH) or the Consumer Prices Index (CPI), for which weights are calculated using more comprehensive national accounts data sources. These sources draw on a wider range of survey and administrative sources than just the LCF.