Chronology of changes in the Consumer Price Index

Since its inception, the CPI has been comprehensively revised on several occasions to implement updated samples and weights, expanded coverage, and enhanced methodologies. The improvements introduced over the years have reflected not only the Bureau’s own experience and research, but also the criticisms and investigations of outside researchers.

The original Consumer Price Index

Began publication of separate indexes for 32 cities (1919): Collected prices in central cities periodically
Developed weights reflecting the relative importance of goods and services purchased by consumers, from a study that BLS conducted in 1917–1919 of family expenditures in 92 industrial centers
Collected prices for major groups: Food, clothing, rent, fuels, house furnishings, and miscellaneous
Limited pricing to items selected in advance to represent their categories
Began regular publication of a national index, the U.S. city average, in 1921: Based index on an un-weighted average of the city indexes
Estimated the U.S. city average back to 1913, using food prices only

The 1940 CPI revision: the first comprehensive revision

Used weights based on a 1934–1936 study of consumer expenditures
Collected prices in the 34 largest cities
Implemented a weighted average of cities for the U.S. city average indexes

Improvements made between the 1940 and 1953 revisions

During World War II: Discontinued the pricing of unavailable items, such as new cars and household appliances
Increased the weight of other items, including automobile repair and public transportation
Adjusted weights in seven cities, using a 1947-1949 survey of consumer expenditures
Adjusted weights based on the 1950 Census
Adjusted rent index to remove “new unit bias” caused by rent control
Added new items to the list of covered items, including frozen foods and televisions

The 1953 CPI revision: the second comprehensive revision

Used weights based on a 1950 survey of consumer expenditures conducted in central cities and attached urbanized areas
Added a sample of medium and small cities
Updated the list of items that the index covered, adding restaurant meals
Expanded the sample of rental units and added homeownership costs
Improved pricing and calculation methods

The 1964 CPI revision: the third comprehensive revision

Based weights on a 1960–1961 survey of consumer expenditures in metropolitan areas
Added single-person households to target population: urban wage earner and clerical worker households
Extended price collection of goods and services to the suburbs of sampled metropolitan areas
Updated the sample of cities, goods and services, and retail stores and service establishments

Improvements made between the 1964 and 1978 revisions

Made quality adjustments for new vehicles at model changeover
Improved treatment of seasonal items

The 1978 CPI revision: the fourth comprehensive revision

Added a new Consumer Price Index: the CPI for All Urban Consumers, or the CPI-U
Renamed the older CPI to the CPI for Urban Wage Earners and Clerical Workers, or the CPI-W
Based weights on a 1972–1973 survey of consumer expenditures and the 1970 census
Expanded the sample to 85 areas (primary sampling units)
Increased minimum frequency for obtaining the prices of goods and services (known as “pricing”) from quarterly to bi-monthly
Implemented monthly pricing in five largest areas
Introduced probability sampling methods at all stages of CPI sampling
Introduced checklists that define each category of spending to clarify what is included or excluded from an item
Developed estimates of the CPI’s sampling error and optimal sample allocation to minimize that error

Improvements made between the 1978 and 1987 revisions

Began systematic replacement of retail outlets and their item samples between major revisions:

Implemented a Point-of-Purchase Survey (POPS)
Selected retail outlets with probability proportional to consumer spending therein
Eliminated reliance on outdated secondary-source sampling frames
Began rotating outlet and item samples every 5 years
Began rotating one-fifth of the CPI pricing areas each year
Introduced rental equivalence concept (January 1983 for the CPI-U; January 1985 for the CPI-W). Additional information on rental equivalence is available in a factsheet.

The 1987 CPI revision: the fifth comprehensive revision

Based weights on the 1982–1984 Consumer Expenditure Survey and the 1980 Census
Updated samples of items, outlets, and areas
Redesigned the CPI housing survey
Improved sampling, data collection, data-processing, and statistical estimation methods
Initiated more efficient sample design and sample allocation
Introduced techniques to make CPI production and calculation more efficient

Improvements made between the 1987 and 1998 revisions

Improved housing estimator to account for the aging of the sample housing units
Improved the handling of new models of vehicles and other goods
Implemented new sample procedures to prevent overweighting items whose prices are likely to rise
Improved seasonal adjustment methods
Initiated a single hospital services item stratum with a treatment-oriented item definition
Discontinued pricing of the inputs to hospital services

The 1998 CPI revision: the sixth comprehensive revision

Based weights on the 1993–1995 Consumer Expenditure Survey and the 1990 census
Updated geographic and housing samples
Extensively revised item classification system
Implemented new housing index estimation system
Used computer-assisted data collection
Added the Telephone Point-of-Purchase Survey (TPOPS) which allows rotation of outlet and item samples by item category and geographic area, rather than by area alone (this survey was previously conducted in person)

Improvements made between the 1998 and 2018 revisions

Developed the Consumer Price Index Research Series (January 1999): an estimate of the CPI for all Urban Consumers (CPI-U) from 1978 to present that incorporates most of the improvements made over that time span into the entire series
Initiated a new housing survey based on the 1990 census (January 1999): Estimated price change for owners’ equivalent rent directly from rents (an estimate of the implicit rent owner occupants would have to pay if they were renting their homes)
Began using a geometric mean formula for most basic indexes (January 1999): Mitigates lower level substitution bias and reflects shifts in consumer spending with item categories as relative price change
Expanded the use of hedonic regression in quality adjustment
Directed replacement of sample items in the personal computer and other categories, to keep samples current
Implemented 4-year outlet rotation to replace 5-year scheme
Implemented biennial weight updates starting in January 2002
Added the Chained Consumer Price Index for All Urban Consumers (C-CPI-U) in August 2002
- Uses more advanced “superlative” index formula (the Törnqvist formula)
- Corrects upper-level substitution bias
Expanded collection of price data to all business days of the month (Before 2004, prices were collected the first 18 business days of the month for the first 10 months of the year and the first 15 business days for November and December.)
Began publishing indexes to three decimal places (January 2007)
Added CPI-E and published it back to 1982 (2008)
- Congress mandated experimental consumer price index for the elderly (62 years of age and older)
- CPI-E has limitations related to the expenditure weights, outlets sampled, items priced and the prices collected

2018 Geographic Revision

Introduced a new geographic sample based on the 2010 Census
Changed the publication frequency for several local area indexes
Established new local area and aggregate indexes
Introduced Census Division-level index data

Changes to the CPI establishment frame (2019-2020)

Replaced Telephone Point-of-Purchase Survey (TPOPS) as source of retail establishment frame with data from the Consumer Expenditure Surveys (CE)
Eliminated redundancies and inefficiencies in survey operations and reduced household burden
Use of Quarterly Census of Employment and Wages business registry to refine the location and address data from the CE

For more on the history of the CPI and price change in the U.S see

Last Modified Date: April 9, 2020