A basket of everyday items, including tea bags, bananas, potatoes and milk, went up in price by nearly eight per cent over the past year, according to the Office for National Statistics.
The figures for the 12 months to June have been released as part of a project to find new ways to monitor the list of products used to calculate inflation.
The new data has been compiled using “web scraping”.
A computer scans the websites of Tesco, Sainsbury’s and Waitrose every day at 5am, recording the prices for each of the 35 items in the Office’s inflation basket.
Nearly 200,000 prices are collected each month, a much larger number than gathered for the Consumer Price Index measure of inflation.
The new figures suggest recent supermarket “price wars” may not have had a consistent impact across the country.
And it says the new data should not be directly compared with the rate of inflation. This is because of the way the figures have been compiled, in particular the variations between prices collected every day (a “chain index”) and the average cost across a fixed period (the “unit price”).
The inconsistency could explain shoppers seeing prices varying more day-to-day than in the official rate of inflation each month.
This would support the findings of the Institute for Fiscal Studies, which has called for statistics to be compiled from more data sources.
