Measuring Price Change for Grains in the U.S. Export Price Indexes
The Bureau of Labor Statistics (BLS) U.S. Export Price Indexes include measures of price change for a variety of grain exports, including wheat, rice, corn, soybeans, and other oilseeds. Grain export indexes have been published since the 1980s. Indexes for wheat and soybean and soybean by-products were first published on a quarterly basis in December 1980 while indexes for feedstuff, corn, soybeans and other oilseeds began quarterly publication in 1984. BLS began publishing the majority of these indexes on a monthly basis in 1994. All estimates are preliminary and subject to revision in each of the 3 months after original publication to reflect the availability of additional information.
Sample Design and Selection
To create the U.S. Export Price Indexes, BLS selects a sample of establishments based upon their relative export trade value during the course of a year. The majority of export indexes are calculated using this sampling methodology. Some of the grains indexes, including corn, wheat, and soybeans, are sampled using a combination of the export sampling methodology and a subset of data from the U.S. Department of Agriculture (USDA).
For grain exports, pricing data are obtained directly from domestic exporters as well as from the USDA. Data from the USDA are used in the calculation of indexes for corn, soybean, wheat, barley and sorghum. For these grains, the USDA’s Farm Service Agency (FSA) Bulk Commodities Division publishes a Daily Market Rates report, which provides prices for specific grain commodities for a number of markets. BLS uses an average of select market rate prices provided in these reports for the first 5 business days of the month.
Regional Trade Value Weights
BLS uses U.S. export data files compiled and supplied by the Foreign Trade Division of the U.S. Census Bureau to recalculate export trade value weights by commodity and domestic region on an annual basis. Data found in these files include the District of Exportation, 10-digit Harmonized Commodity codes, and the associated dollar value for the commodity traded in the district for the year. Further refinement of these data are necessary, as the market prices obtained from the USDA for different grain commodities are collected from multiple markets and the actual trade weight needs to be assigned for the relevant district/regions and commodities provided by the U.S. Census Bureau.
The trade value data received from the U.S. Census Bureau are aggregated to correlate with the market price information obtained from USDA. The District of Exportation on the Census Bureau report is mapped to a corresponding region using knowledge of geographical proximity and transportation factors such as available waterways. For example, Toledo market rate prices provided in the USDA Market reports correspond with the Toledo Lakes region, while Minnesota market rate prices correspond with the Duluth/Lake Superior region.
The Harmonized Commodity codes in the Census Bureau report must be mapped with the grain commodity prices provided by the USDA Daily Market Reports. There is a direct association between the Harmonized code and the commodity price provided for both soybean and sorghum. Barley, corn, and wheat, however, require an extra step to create the correlation between the USDA Market Reports and the Harmonized Commodity code provided by the U.S. Census Bureau. For both barley and corn, the Harmonized codes are aggregated to correlate with the respective grain commodity price provided by the USDA. On the other hand, prices for three classes of wheat that are collected from the USDA fall under the same Harmonized code. The trade weight associated with the Harmonized code for wheat needs to be distributed to the appropriate wheat classes. The USDA’s Economic Research Service (ERS) provides yearly total exports by wheat class and the proportional weight of the wheat classes can be calculated using these export totals.
Once the trade value data from the U.S. Census Bureau for both commodity and region are mapped with the USDA Daily Market Reports, the regional trade value weights are calculated using the dollar values provided in the Census Bureau files. The trade value weights are updated annually with a two year lag.
Access the Data
The most recent data for this industry can be found in the U.S. Import and Export Price Indexes Economic News Release. These data are available in a variety of formats on the BLS website (www.bls.gov/mxp).
Additional information on the U.S. Import/Export Price Indexes can be found in "International Price Indexes," BLS Handbook of Methods, Bulletin 2490 (Bureau of Labor Statistics, 1997), Chapter 15. This chapter also is available on the BLS Internet site (www.bls.gov/mxp) under the topic "Publications." You may contact the International Price Program of the BLS by telephone at (202) 691-7101 or by email.
Information in this report is in the public domain and may be reproduced without permission. This information is available to sensory impaired individuals upon request. Voice phone: (202) 691-5200; TDD Phone: (202) 691-5200; TDD message referral phone: 1-800-877-8339.
Last Modified Date: November 30, 2012