Methods of CPI/HICP price collection
There are two basic price collection methods: local and centralised.
Local collection is used for 478 of the 615 item headings; pre pandemic prices were collected by approximately 80 price collectors in retail outlets in 84 locations around the country. Approximately 48,000 quotations were obtained by this method. These item headings account for 49.2% of the total weight of the CPI basket.
Centralised collection is used for 137 of the 615 item headings; prices are collected centrally by the CSO with minimal field work. In practice, this involves the use of postal, e-mail and telephone enquiries along with internet price collection. Approximately 3,000 quotations are obtained by this method. These item headings account for 50.8% of the total weight of the CPI basket
Impact of pandemic on CPI data collection
The CSO sustained the following contingency measures to collect CPI price data for throughout the pandemic which were initially implemented in April 2020:
Redesign of local price collection
Maximising the benefits of the contingency measures used throughout the last 22 months to calculate the CPI, a hybrid collection method which utilises multiple sources is being implemented.
This will include the use of price collectors in the field, online pricing, webscraping methods and receiving price files directly from retailers. Utilising these multiple sources will lead to the reduction of operational risk by providing a secure supply of price information and will improve the quality and accuracy of inflation statistics.
Return of price collectors
CPI Price collectors returned to in store pricing in January 2022. This return comprised of 30 price collectors entering multiple retail outlets in 30 locations around the country and they collected approximately 12,000 prices. This has allowed for comparison in February 2022 and for prices collected in stores to be included in the calculations of the CPI for the first time since March 2020. This method allows for price collection in localised stores and stores that have a minimal or no online presence which was not possible throughout the pandemic.
CSO statistical publication, , 11am