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Consumer Price Index
 Table 1. Improvements to the Consumer Price Index for All Urban Consumers (CPI-U) since 1978, and their effect on the CPI retroactive series using current methods (R-CPI-U-RS).
Change Description Year implemented in CPI-U CPI-U-XRS incorporates estimate of change from:

Use of rental equivalence to measure changes in homeowner costs

Changed homeowners’ component from cost of purchase to value of rental services 1983 1978-1982

Rental vacancy imputation

Employed new method for imputing price change for rental vacancies 1985 1978-1984

Quality adjustment of used car prices

Prices of used cars adjusted for differences in quality after model changeovers 1987 1978-1986

Quality adjustment of sampled housing units to reflect aging

Rental values in CPI sample were adjusted for aging 1988 1978-1987

Quality adjustment of apparel prices

Regression models used to adjust apparel prices for changes in quality when new clothing lines are introduced 1991 1978-1990

Treating shifts between brand name and generic drugs as price changes

Introduced new procedures that allow generic drugs to be priced when a brand drug loses its patent 1995 1978-1994

Change in shelter formula: elimination of composite estimator

Replaced composite estimator with a 6-month chain estimator. Under-reporting of 1-month rent changes had resulted in missing price change in residential rent and homeowners’ equivalent rent 1995 1978-1994

Change in shelter formula: rental equivalence improved estimator

Modified imputation of homeowners’ implicit rent to eliminate upward drift property of previous estimator 1995 1987-1994

Elimination of functional form bias for CPI food-at-home categories

Introduced “seasoning” procedures to eliminate upward bias derived from the setting of base period prices of newly initiated items 1995 1978-1994

Elimination of functional form bias for other CPI commodity and service categories

Extended food-at-home seasoning procedures to remainder of commodities and services. Base period prices left unchanged in most noncomparable substitutions 1996 1978-1996

Quality adjustment of personal computer prices

Regression models used to adjust personal computer prices for changes in quality 1998 1987-1997

Elimination of automobile finance charges

Deemed out of scope 1998 1978-1997

Quality adjustment of television prices

Regression models used to adjust television prices for changes in quality 1999 1978-1998

Accounting for consumer substitution within CPI item categories

The geometric formula now used assumes a modest degree of consumer substitution within most CPI item categories 1999 1978-1998

Treating mandated pollution control measures as price increases

Changes in pollution control regulations now viewed as price changes and not quality changes 1999 1978-1998

Quality adjustment of audio equipment prices

Regression models used to adjust audio equipment prices for changes in quality 2000 1978-1998

Quality adjustment of other video equipment prices

Regression models used to adjust other video equipment prices for changes in quality:
video cameras
video cassette recorders
2000
1987-1999
1987-03/2000

Quality adjustment of refrigerators/freezers

Regression models used to adjust refrigerators/freezers for changes in quality 2000 1978-06/2000

Quality adjustment of clothes washers

Regression models used to adjust prices of clothes washers for changes in quality 2000 1978-09/2000

Quality adjustment of clothes dryers

Regression models used to adjust prices of clothes dryers for changes in quality 2000 1978-09/2000

Quality adjustment of microwave ovens

Regression models used to adjust prices of microwave ovens for changes in quality 2000 1978-06/2000

Quality adjustment of college textbooks

Regression models used to adjust prices of college textbooks for changes in quality 2000 1978-06/2000

Revision of shelter indexes for 1999

To adjust for an error in the calculation of the rent and owners’ equivalent rent indexes for 1999. 2000 1999

More frequent weight updates

Weights are now updated in the CPI every two years instead of approximately every ten years. 2002 1990-95

Prescription drugs formula change

The Prescription drug index is now calculated using a Laspeyres formula 2016 2010-2015

Last Modified Date: August 5, 2020