Consumer Price Index - All Urban Consumers (Chained CPI)

the chained consumer price index for all urban consumers was introduced with the release of july data in august 2002 designated the c cpi u the index supplements the existing consumer price indexes already produced by the bls the cpi for all urban consumers cpi u and the cpi for urban wage earners and clerical workers cpi w the c cpi u employs a tornqvist formula and utilizes expenditure data in adjacent time periods in order to reflect the effect of any substitution that consumers make across item categories in response to changes in relative prices the new measure is designed to be a closer approximation to a cost of living index than the present measures the use of expenditure data for both a base period and the current period in order to average price change across item categories distinguishes the c cpi u from the existing cpi measures which use only a single expenditure base period to compute the price change over time