In a news release from 11 September 2017, Statistics Iceland announced that the impact of changes in consumer behaviour on the consumer price index (CPI) would be studied in the light of recent openings of new stores, and whether the CPI should be evaluated and adjusted accordingly.

The study was primarily based on data from the Household Expenditure Survey for 2017, where participants provide Statistics Iceland with information on where goods are bought by delivering purchase receipts, which provide information on changes in outlet choices. In addition, company specific turnover data was examined. Furthermore, the price measurements were enhanced and time series analysed specifically.

The results of the study indicate that Icelandic households have changed their purchasing behaviour substantially and have been susceptible to the new stores. Consequently other stores and companies, already in the same market, have lowered prices of various products, altering the market equilibrium. However, the provision of a reliable comparison between stores is complex, for example the product supply and packages may not be fully comparable between stores.

The comparison of prices in the new stores and preceding stores has shown, with available data, that the impact of the changes is already reflected in the consumer price index.

The consumer price index is rebased annually with respect to March each year. Statistics Iceland will during the next rebasing practice in March 2018 re-evaluate the outlet weights in the CPI with respect to household consumption measurements from more extensive data sources than are available now and include the effect appropriately.