More information and data on the RPI and other measures of inflation will be provided in the Participants' Pack. Any individual price change could cause the measured rate of inflation to change, particularly if it is large or if the item has a significant weight in the price index. But we are more interested in the general increase in prices rather than individual price changes. A large rise in the price of petrol, for example, might affect the overall rate of inflation. But unless this price carried on rising, the annual rate of inflation would eventually fall back again - the example in the box below explains this, if you want to know more.
Events affecting a range of prices can also result in a change in the inflation rate.
If petrol prices remained unchanged after that, the annual rate of inflation would then fall back in February 2001. So, although the price of petrol remains at the higher level, annual inflation is not higher after a year or more. But only if the exchange rate keeps falling will this influence on inflation continue. Price changes like those described can have other indirect effects on inflation. But individual price changes in themselves don't have a lasting impact on the inflation rate.