TECHNICAL NOTE                                                

Import and Export Merchandise and Services Price Indexes - All indexes use a modified Laspeyres 
formula and are not seasonally adjusted. Price indexes are reweighted annually, with a 2-year lag in the 
weights. Published series use a base year of 2000=100 where possible. More detailed index series and 
additional information may be obtained at www.bls.gov/mxp or by calling (202) 691-7101.

Merchandise Goods Classification Systems - The merchandise price indexes are published using three 
classification systems. Items are classified by end use according to the Bureau of Economic Analysis 
Classification System, by industry according to the North American Industry Classification System 
(NAICS), and by product category according to the Harmonized System (HS). While classification by 
end use and product category are self-explanatory, some notes are in order for classifying items by 
industry. In the NAICS imports and exports tables, items are classified by output industry, not input 
industry. As an example, NAICS import index 326 (plastics and rubber products manufacturing) include 
outputs such as manufactured plastic rather than inputs such as petroleum. The NAICS classification 
structure also matches the classification system used by the Producer Price Index (PPI) to produce the 
NAICS primary products indexes.

Import Price Indexes - Products have been classified by the Harmonized Tariff Schedule of the United 
States Annotated (TSUSA). Import prices are based on U.S. dollar prices paid by the U.S. importer. The 
prices are generally either "free on board" (f.o.b.) foreign port or "cost, insurance, and freight" (c.i.f.) 
U.S. port transaction prices, depending on the practices of the individual industry. The index for crude 
petroleum is calculated from data collected by the U.S. Department of Energy.  

Export Price Indexes - Products have been classified by the Harmonized Schedule B classification 
system of the U.S. Bureau of the Census. The prices used are generally either "free alongside ship" 
(f.a.s.) factory or "free on board" (f.o.b.) transaction prices, depending on the practices of the individual 
industry. Prices used in the grain index, excluding rice, are obtained from the U.S. Department of 
Agriculture.

Services Price Indexes - Starting in September 2008, the import air passenger fares indexes represent 
changes in the average revenue per passenger received by foreign carriers from U.S. residents and are 
calculated from data obtained from an airline consulting service. These data include tickets sold by 
travel agencies and travel websites. Tickets sold directly by the airlines are excluded, as are frequent 
flyer tickets generally. Starting in January 2008, the export air passenger fares indexes represent changes 
in the average revenue per passenger received by U.S. carriers from foreign residents and are calculated 
from data collected directly from airlines. These data include frequent flyer tickets and those sold by 
consolidators. Taxes and fees are included in the import air passenger fares indexes and excluded from 
the export air passenger fares indexes. The air freight indexes are calculated from data collected directly 
from airlines. These data exclude mail and passenger baggage. The scope of the service being priced is 
the movement of freight from airport to airport only, and does not include any ground transportation or 
port service. The air freight indexes are presented using two definitions: balance of payments (which 
represent transactions between U.S. and foreign residents) and international (which represent 
transactions inbound to and outbound from the U.S.). Fact sheets specifying detailed information for 
each services industry are available at www.bls.gov/mxp under "MXP Publications."

Import Indexes by Locality of Origin - Prices used in these indexes are a subset of the data collected 
for the import price indexes. Beginning with January 2002, the indexes are defined by locality of origin 
using a nomenclature based upon the North American Industry Classification System (NAICS). 
Nonmanufactured goods are defined as NAICS 11 and 21, and manufactured goods are defined as 
NAICS 31-33. 

Relative Importance - A relative importance is a specific index's price-updated value share (expressed 
as a percentage) of overall imports or exports at a specific point in time. Relative importance values are 
affected by the trade weights at the point indexes are reweighted and index changes relative to other 
indexes since the reweight point. If an index is rising in value relative to other indexes over time, the 
relative importance will increase as well. 
 
Revision Policy - To reflect the availability of late reports and corrections by respondents, monthly data 
may be revised in each of the 3 months after original publication. After 3 months, no further data 
revisions take place. For example, data first published in the January release will be subject to revision 
in the releases for February, March, and April.

Uses of the Data - The primary use of the indexes is to deflate trade statistics, notably the foreign trade 
sector of the National Income and Product Accounts (NIPA) constructed by the Department of 
Commerce. Other published indexes are useful for general market analysis. For trade in international 
services, balance of payments indexes are used for deflating NIPA, while international indexes are more 
appropriate for market analysis. Merchandise and services indexes also can be used to study U.S. 
competitiveness and to compute price elasticities, and the merchandise import indexes by country or 
region of origin are useful in terms of trade analysis.

Email Subscription - The U.S. import and export price indexes news release is available through an 
email subscription service at www.bls.gov/bls/list.htm. 
 
Additional Information - More detailed data are available on the Import/Export Price Indexes home 
page at www.bls.gov/mxp. For import and export price indexes data requests, send an email to 
mxpinfo@bls.gov.   

Information from this release will be made available to sensory impaired individuals upon request.  
Voice phone: (202)-691-5200; Federal Relay Service: 1-(800)-877-8339.