Table B-2e. Estimated Standard Errors for Shipment Characteristics by Total Modal Activity for the United States: Percent of Total for 2002, 1997, and 1993
Monday, July 2, 2012
Table B-2e. Estimated Standard Errors for Shipment Characteristics by Total Modal Activity for the United States: Percent of Total for 2002, 1997, and 1993
[Estimates are shown as percents and are based on data from the 2002, 1997, and 1993 Commodity Flow Surveys]
| Mode of transportation | Ton-miles (percent) | ||
|---|---|---|---|
| 2002 | 1997 | 1993 | |
| Total | – | – | – |
| Truck | 1.5 | 1.1 | 0.9 |
| Rail | 1.6 | 1.5 | 0.9 |
| Shallow draft | 0.6 | 0.4 | 1.0 |
| Great Lakes | 0.3 | 0.2 | 0.3 |
| Deep draft | 0.4 | 0.5 | 0.5 |
| Air | – | – | – |
| Parcel, U.S.P.S. or courier | – | – | – |
| Pipeline | S | S | S |
| Other and unknown modes | 0.2 | 0.3 | 0.5 |
KEY:
– Represents data cell equal to zero or less than 1 unit of measure.
S Estimate does not meet publication standards because of high sampling variability or poor response quality.
NOTES: 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/cfs.
SOURCE: Bureau of Transportation Statistics (USDOT) and U.S. Census Bureau, 2002 Commodity Flow Survey, United States Data, December 2004.