Table B-2c. Estimated Measures of Reliability for Shipment Characteristics by Total Modal Activity for the United States: 2002 and 1993

Table B-2c. Estimated Measures of Reliability for Shipment Characteristics by Total Modal Activity for the United States: 2002 and 1993

[Estimates are shown as percents and are based on data from the 2002 and 1993 Commodity Flow Surveys]

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Mode of transportation Ton-miles
CV
Std. error of percent Average miles per shipment
CV
Std. error of percent
2002 1993 2002 1993
Total 3.7 3.4 6.5 2.8 3.9 6.1
Truck 2.8 1.4 4.5 3.6 1.3 4.6
Rail 7.6 5.4 12.6 6.1 5.2 7.7
Shallow draft 9.4 11.1 14.8 13.1 5.1 16.3
Great Lakes 18.1 24.6 43.5 16.0 14.4 15.0
Deep draft 17.3 14.0 19.2 11.1 5.4 11.0
Air 15.7 6.2 25.2 4.3 3.9 8.0
Parcel, U.S.P.S. or courier 4.2 3.6 8.0 2.3 3.3 4.9
Pipeline S S S S S S
Other and unknown modes 9.7 11.6 7.2 13.0 14.4 11.0

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.
CV Coefficient of variation of number.

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.