The CPI(C) was formerly known as the Hang Seng CPI and was compiled by Hang Seng Bank. Starting from the reference month of July 1999, the data collection and compilation work of the index have been taken up by the Census and Statistics Department and the index has been renamed as CPI(C). Apart from being a standardization of titles, the renaming does not affect the compilation methodology nor the continuity of the index series. The CPI(C) is compiled based on expenditure patterns obtained from a Household Expenditure Survey conducted during October 2014 to September 2015. The CPI for earlier periods is compiled based on old patterns and has been re-scaled to the new base period (i.e. October 2014 - September 2015) for linking with the new index series. The CPI(C) relates to 10% of households, which are in the relatively high expenditure range. The average monthly household expenditure range of this group was broadly equivalent to HK$46,400 - HK$93,800 after taking into account of price changes since the base period and adjusting to the price level of 2017.