Table B-1c. Estimated Standard Errors for Hazardous Material Shipment Characteristics by Mode of Transportation for the United States: Percentage of Total for 2012 and 2007
(Estimates are based on data from the 2012 and 2007 Commodity Flow Surveys)
|Mode of transportation||
|Ton-miles (1)— standard error|
|Air (includes truck and air)||Z||0.1||Z||S||Z||S|
|Parcel, U.S. Postal Service, or courier||0.1||0.1||Z||0.0||Z||0.0|
|Truck and rail||0.1||0.1||0.1||0.1||0.8||0.5|
|Truck and water||S||0.3||S||0.3||S||0.7|
|Rail and water||Z||0.1||0.1||0.1||0.2||0.2|
|Other multiple modes||0.0||0.4||0.0||0.5||0.0||1.2|
KEY: S = Withheld because estimate did not meet publication standards.
X = Not applicable.
Z = Rounds to zero.
(1) Ton-miles estimates are based on estimated distances traveled along a modeled transportation network. See “Mileage Calculations” section for additional information.
(2) “Truck” as a single mode includes shipments that were made by only private truck or only for-hire truck.
(3) Estimates for pipeline exclude shipments of crude petroleum (SCTG 16).
NOTES: Value-of-shipments estimates have not been adjusted for price changes. Appendix B tables provide estimated measures of sampling variability. The Introduction and appendixes give information on confidentiality protection, sampling error, nonsampling error, sample design and definitions. Links to this information on the Internet may be found at <www.census.gov/econ/cfs>.
SOURCE: U.S. Department of Transportation, Bureau of Transportation Statistics and U.S. Department of Commerce, U.S. Census Bureau, 2012 Economic Census: Transportation Commodity Flow Survey, December 2014.