|Unit||Index Dec1983=100, NSA|
Not Seasonally Adjusted
The U.S. Bureau of Labor Statistics (BLS) reports monthly consumer price indices (CPI) for the United States. CPI measures the change in prices paid by consumers for goods and services. Figures are reported using various bases, both seasonally adjusted (SA) and not seasonally adjusted (NSA).
The BLS reports CPI for two different population groups:
Data is collected each month in 75 urban areas in the United States. There are about 5,000 housing units and 22,000 retail establishments sampled. Taxes associated with the purchase of goods or services are included in the price and index. Data is typically collected by personal visits or phone calls by BLS representatives.
The index is calculated by aggregation and using weights for each items in a specific location. The weights represent their importance in the spending for each population group. Localized data is then combined to calulcate a U.S. city average.
Area indexes do not measure differences in the level of prices among cities; they only measure the average change in prices for each area since the base period.
The indexes have a base of 1982-84=100, unless otherwise noted. This means that the average of the monthly index values is 100 over the 36 months in 1982 through 1984. An index represents the relative change over time since a base period. For example, an index of 120 denotes an increase of 20%, and 75 is a decrease of 25%.
There are various base periods in this data set depending on the type of expenditure and geographical area. The base periods are: Oct1967, Jan1978, Feb1978, Apr1978, Nov1977, Dec1977, 1982-84, Nov1982, Dec1982, Dec1983, Nov1984, Dec1986, Dec1988, Nov1996, Dec1996, Nov1997, Dec1997, Dec2005, Dec2007, Dec2009, and Dec2017.
Geographic coverage is all four census regions, all nine census divisions, 23 MSAs per Census 2010 delineations, and 10 class-sizes (population groups by area).
Seasonally adjusted (SA) data are computed using seasonal factors derived by the X-13ARIMA-SEATS seasonal adjustment method. Factors are updated each February, and are used used to revise the previous five years of SA series.
|Area Name||Geo Code||Frequency|
|U.S. City Average||IUSA||Monthly|
|Northeast Census Region||CNER||Monthly|
|Midwest Census Region||CNCR||Monthly|
|Southern Census Region||CSOR||Monthly|
|Western Census Region||CWER||Monthly|
|New England Census Division||CNEC||Monthly|
|Middle Atlantic Census Division||CMAC||Monthly|
|East North Central Census Division||CENC||Monthly|
|West North Central Census Division||CWNC||Monthly|
|South Atlantic Census Division||CSAC||Monthly|
|East South Central Census Division||CESC||Monthly|
|West South Central Census Division||CWSC||Monthly|
|Mountain Census Division||CMTN||Monthly|
|Pacific Census Division||CPAC||Monthly|
|New York-Newark-Jersey City, NY-NJ-PA||IUSA_MNEY||Monthly|
|St. Louis, MO-IL||IUSA_MSTL||Bimonthly|
|Miami-Fort Lauderdale-West Palm Beach, FL||IUSA_MMIA||Bimonthly|
|Atlanta-Sandy Springs-Roswell, GA||IUSA_MATL||Bimonthly|
|Tampa-St. Petersburg-Clearwater, FL||IUSA_MTAM||Bimonthly|
|Dallas-Fort Worth-Arlington, TX||IUSA_MDAL||Bimonthly|
|Houston-The Woodlands-Sugar Land, TX||IUSA_MHOU||Bimonthly|
|Los Angeles-Long Beach-Anaheim, CA||IUSA_MLOS||Monthly|
|Riverside-San Bernardino-Ontario, CA||IUSA_MRIV||Bimonthly|
|San Francisco-Oakland-Hayward, CA||IUSA_MSAF||Bimonthly|
|San Diego-Carlsbad, CA||IUSA_MSAN||Bimonthly|
|BLS size class B/C||CTY_BC||Population: 2,500,000 or less|
|Northeast - Size Class B/C||CNER_BC|
|Midwest - Size Class B/C||CNCR_BC|
|South - Size Class B/C||CSOR_BC|
|West - Size Class B/C||CWER_BC|
|BLS size class A||CTY_A||Population: more than 2,500,000|
|Northeast - Size Class A||CNER_A|
|Midwest - Size Class A||CNCR_A|
|South- Size Class A||CSOR_A|
|West - Size Class A||CWER_A|
As of January 2022, we compute two special metrics related to the COVID-19 pandemic. viz., the contributions to CPI-U growth of two groups of items: those that are constrained by supply chains, and those associated with pandemic reopening.
As of June 2022, we calculate the contribution to CPI-U growth for 30 major expenditure items.
Yes, when expenditure weights are updated.
Yes, when seasonal factors are updated. This is performed prior to the release of January data, and applies to the prior five years. The source writes:
The Consumer Price Index (CPI) produces both unadjusted and seasonally adjusted data. Seasonally adjusted data are computed using seasonal factors derived by the X-13ARIMA-SEATS Seasonal Adjustment Method. These factors are updated with the release of January data in February and reflect price movements from the previous calendar year. The new factors are used to revise the previous 5 years of seasonally adjusted data; older seasonally adjusted indexes are considered to be final.
Topline year over year calculations are reported in the BLS press releases as non-seasonally adjusted (XCPIU.IUSA). There may be slight differences between Y/Y figures for SA and NSA series. Because the seasonal factors differ each year, the ratio of index numbers used to compute the change are not necessarily exactly comparable.
At the source: