U.S. Goods Trade for the Gulf Region: Technical Documentation

This press release is a preliminary release created in response to the disruption of trade activity in the Gulf region caused by hurricanes Katrina and Rita. This release includes data for all ports in five districts bordering the Gulf of Mexico. These districts are Tampa, FL; Mobile, AL; New Orleans, LA; Port Arthur, TX; and Houston, TX.

Analysis of Gulf region export and import goods data indicates the value of preliminary data should be between 70 and 90 percent of the final value reported in the regular monthly trade report, with wider variations by district, port, and industry group.

The data in this report are preliminary and subject to change. Preliminary data are compiled from a partial accumulation of import and export transaction received and processed for the reporting period. Caution should be exercised when using these statistics as the level can fluctuate from preliminary to final. Data for months prior to the current statistical month are unrevised and reflect totals when they were originally published or processed. Exports are based on port of exportation and exclude exports to Puerto Rico and other U.S. territories and possessions. Imports are based on port of unlading and include general imports only.

Nonsampling Error

The data in this release are an enumeration of documentation collected by the U.S. Customs and Border Protection (CBP) and are not subject to sampling error. Quality assurance procedures are performed at every stage of collection, processing and tabulation of the information. The data are subject to nonsampling errors, which include reporting errors, undocumented shipments, timeliness, data capture errors, and errors in low value estimation. For more information on these types of errors please see the Information on Goods and Services section of the FT900 - U.S. International Trade in Goods and Services, page 26.

In addition to the reporting errors that affect the general merchandise trade statistics, there are reporting errors that specifically affect data tabulated by port. In general, the businesses or individuals that report the data may not be the same as those who physically convey the shipments. This can lead to inaccurate information about where a shipment enters or exits the United States and how it is transported. The U.S. Census Bureau (Census Bureau) quality assurance procedures include checking that reported ports are valid CBP ports and performing relational checks between the ports and the method of transportation. In addition, the Census Bureau is considering extracting transportation information directly from the manifest. However, the port data are still subject to this type of reporting error.

The Census Bureau recommends that data users incorporate this information into their analyses, as nonsampling error could impact the conclusions drawn from the results.

Data Quality

The CBP assigns official ports and determines the type and direction of trade that is conducted at that port. In some cases, a port may receive imports but no exports, or vice versa.

The following types of shipments are included for statistical purposes in special CBP districts and are not reported by geographical location of the individual CBP district of entry or exportation: Vessels under their own power or afloat (imports and exports), Low-valued imports and exports, Mail shipments (exports only), Norfolk, VA-Charleston, SC-Mobile, AL (Exports of bituminous coal), Wilmington, NC-Savannah, GA (Exports of cotton linter pulp).

Confidentiality

The Census Bureau has modified or suppressed some data in this release to protect confidentiality. Title 13 United States Code, Section 9, prohibits the Census Bureau from publishing results in which an individual's or business' data can be identified. For more information on how the Census Bureau protects the confidentiality of data, see the disclosure limitation topics listed below as appropriate.

Disclosure Limitation

Disclosure limitation is the process for protecting the confidentiality of data. A disclosure of data occurs when someone can use published statistical information to identify either an individual or business that has provided information under a pledge of confidentiality. The techniques used by the Census Bureau to protect confidentiality in tabulations vary, depending on the type of data.

Data for two or more product codes may be combined to protect confidentiality. Furthermore, statistics for two or more CBP ports may be combined and published under an arbitrary designation to limit disclosure. The value may be excluded from an individual CBP port as a solution to disclosure situations. In addition, value for a particular commodity may be placed in separate ports. Consequently, statistics for individual ports may be understated or overstated due to the suppression of the value of the affected commodities.

Definitions of Terms

• Port:

  • Imports: Port of Unlading - The port where merchandise is unloaded from the importing vessel or aircraft. It is not necessarily the same port the shipment clears CBP. For overland shipments, they are one and the same.
  • Exports: Port of Export - The CBP port where the merchandise is loaded on the vessel or aircraft which takes the merchandise out of the country. For other overland transportation, the port through which the merchandise crosses the U.S. border into a foreign country.

• NAICS Code: 3-digit North American Industry Classification System code. The first two digits of the code designate the sector that represent general categories of economic activities and the third digit designates the sub-sector.

• Value:

  • Imports: The import data is based on CBP value, generally defined as the price actually paid or payable for merchandise when sold for exportation to the United States, excluding U.S. import duties, freight, insurance and other charges incurred in bringing the merchandise to the United States.
  • Exports: Exports are valued on a free alongside ship (FAS) basis, which reflects transaction price including inland freight, insurance and other charges incurred in placing the merchandise alongside the ship at the port of export.

• Method of Transportation: The mode of transportation by which the merchandise is imported or exported. For this report, shipments by vessel, air and all other modes of transportation are included in the total value for each port. Vessel values are also presented separately.