Documentation
Overview
The Quarterly Food-at-Home Price Database (QFAHPD) is
constructed from household food-at-home purchase data from Nielsen
Homescan data. The Homescan data contain information on
household-level purchases of both Universal Product Code (UPC)
foods--most packaged and canned food--and random-weight (non-UPC)
items such as fresh fruits or vegetables.
ERS created the food groups to correspond with the 2005 Dietary Guidelines for Americans and to
capture price premiums for convenience and processing. ERS
researchers aggregated the food purchases to estimate
household-level quarterly prices for over 50 food groups. The
household-level prices were then aggregated to estimate quarterly
market-level prices. Prices are presented in dollars per 100 grams
of food as purchased by consumers. See Methodology Behind the Quarterly Food-at-Home Price
Database.
Two Versions of QFAHPD
The original version of the Quarterly Food-at-Home Price
Database (QFAHPD-1)
contains prices for 52 food groups based on both UPC-coded and
random-weight food purchases. Quarterly prices are available
for:
- 26 metropolitan markets for 1999-2006, and
- 9 nonmetropolitan areas for 2002-2006 and 4 nonmetropolitan
areas for 1999-2001.
A second version of the Quarterly Food-at-Home Price Database
(QFAHPD-2)
contains prices for 54 food groups based on only UPC-coded food
purchases. Quarterly prices are available for:
- 26 metropolitan and 9 nonmetropolitan markets for
2004-2010.
- A redefined carbonated nonalcoholic beverage group, which now
excludes diet versions of beverages.
- Two new food groups: 1) diet carbonated beverages, and 2)
unsweetened coffee and tea. Dry weights for coffee and tea have
been converted to liquid equivalents, assuming that 2 grams of dry
tea leaves and 10 grams of dry coffee yield 180 ml of liquid
beverage.
Since 2007, Homescan data have included less detailed
information about random-weight food items so that these purchases
could not be incorporated into estimates of prices for food groups
that include random-weight items. Because random-weight items are
often priced quite differently than UPC-coded items, prices for
2007 and after are not comparable with prices for earlier years for
food groups with random-weight items. The QFAHPD-2 was therefore
developed using only UPC-coded purchases for the years 2004-2010,
and prices are constructed consistently across those years.
Revisions
Minor changes were made to both the QFAHPD-1 and QFAHPD-2 for 8
food groups (for all years) that include random-weight purchases.
For the QFAHPD-1, minor changes were made for all food groups in
1999-2001 that include random-weight purchases. These changes were
necessary to incorporate corrections made to the raw Homescan data.
See the Read Me tab in the Excel data files
for more information.
Resources
Methodology Behind
the Quarterly Food-at-Home Price Database--provides an indepth
discussion of how the QFAHPD database was constructed, along with
basic findings about food price variation across geographic areas
and price differentials within food groups between markets.
Codebooks are available for researchers and others to analyze
the data and conduct research. Use Codebook-1 
for QFAHPD-1 and Codebook-2 for QFAHPD-2. Users can download the data
by clicking on the spreadsheet for the specific food group.