FOI reference: FOI-2025-3015
You asked
I'm writing to ask for more information about the internal analysis you mentioned in your response to FOI-2023-1237 ("Methodology on prices collection for grocery items," 11 August 2023).
Could you please share any data, documents, and reports that explain how the analysis was carried out, what data was used, and what the main findings were?
We said
Thank you for your request for information on the effect of loyalty card discount schemes on inflation.
In 2023, we carried out an informal (internal) analysis to judge the effect loyalty card discounts would have on our inflation measures if they were included. Please see the associated download, which provides the analysis requested.
At the end of 2022, we started collecting loyalty card prices alongside the prices used for live production of our consumer price statistics. A simple exercise was carried out to produce a dataset of prices with the shelf-price swapped out for the loyalty card price for those products on discount. This dataset was then run through the standard calculations for producing inflation measures.
This exercise did not produce evidence that a hypothetical index created by using the discount prices would be materially different to published Consumer Prices Index (CPI) at the headline or divisional level.
As part of our ongoing efforts to improve the accuracy and relevance of consumer price statistics, we plan to introduce grocery scanner data into the measurement of consumer price inflation from February 2026, with the first results published in March 2026. This development is outlined in our Introducing grocery scanner data into consumer price statistics article.
One of the key advantages of scanner data is its ability to capture a wider range of promotional activity, including multibuy offers and loyalty scheme discounts. As scanner data include exact sales revenues at the product level, we can more accurately account for the uptake of these promotions, leading to a more precise reflection of actual consumer spending patterns.
While we publish price microdata for our main measures of inflation in our Consumer price inflation consumption segment indices and price quotes dataset, we are not able to share the extra fields collected covering discounts, as this would allow individual businesses to be identified. Section 39 of the Statistics and Registration Service Act 2007 (SRSA) prohibits the disclosure of information that would identify an individual or a corporate body. As such, the exemption found under Section 44(1) of the Freedom of Information Act 2000 (FOIA) applies. It is also for this reason that some material in the slide deck provided has been redacted.