§ Mr. SpellerTo ask the Chancellor of the Exchequer if he has any plans to alter the Laspeyres-based formula for the retail prices index.
§ Mr. RyderNo. The Laspeyres formula, which gives each item a relative importance or "weight" in accordance with the consumption pattern in a specified base period, is recognised throughout the world as the most satisfactory method of constructing a regular consumer price index. The particular variant used for the United Kingdom retail prices index, known as the "chain Laspeyres" formula, minimises the disadvantages of using historical consumption patterns by updating the weights at the beginning of each year.