Since 1999, the CPI has used two different formulas in computing basic indexes. A geometric means formula is used for most items, reflecting that consumers may substitute within CPI categories as relative prices change. However, for some goods and services, such substitution isn't realistic. For these, a Laspeyres formula is still used. The R-CPI-U-L differs from the official CPI-U in that a Laspeyres formula is used for all categories; this corresponds to the pre-1999 methodology of the CPI. Comparing the CPI-U and R-CPI-U-L allows for estimation of the impact of consumer substitution at the lower level (within CPI item categories).
In conjunction with the R-CPI-U-G, the R-CPI-U-L is used by researchers to understand consumer substitution and the impact of the geometric means formula.
The R-CPI-U-L data are unofficial and designed for research purposes.
Monthly R-CPI-U-L data are available from 1999 forward for all published CPI-U series in Excel or SAS output.
Data are available upon request by contacting the CPI Information Office via email or phone: (202) 691-7000.
Additional information is available in the CPI research series using current methods, 1978-98 Monthly Labor Review article.
Last Modified Date: July 17, 2020