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.

Coefficients of the regression equation (Robust/ Huber) of the average price of mobile phones and its characteristic variables in the 31 st and 32 nd weeks of 2022.

The significance of the regression equation between the average price of mobile phones and its characteristic variables in 57 weeks from August 2022 to September 2023.

From August 2022 to September 2023, the average price of mobile phones for 57 weeks and its characteristic variable regression equation goodness of fit.