To ask the President of the Board of Trade what studies have been made of supermarket pricing policies; and what percentage are supermarket prices in the total shopping basket monitoring that comprises the retail prices index data. [35192]

The Office of Fair Trading keeps supermarket behaviour under review. A 1992 OFT review of market concentration and the profitability of the leading supermarket chains provided no basis for concluding action under the competition legislation was needed.For the calculation of the retail prices index, the major supermarkets are given weights proportionate to their estimated market shares. These weights vary from item to item and from month to month. An estimate of supermarkets' share of the total RPI basket could be produced only at disproportionate cost.