This section presents two tables for each state on commodity movements originating in and destined to each state. The first table for each state summarizes shipments by major commodities, major destinations, distance, and modes of transportation. Data on the mode of transportation are aggregated. For example, the truck category includes for-hire, private, and a combination of both; the air category includes truck and air. Note that each state's share of total U.S. shipments is calculated using both final state data and national data measured in the 2002 Commodity Flow Survey.
Because CFS data are estimates based on a sample, the data are subject to sampling errors. The second table for each state provides the 90-percent confidence intervals for each estimate. A confidence interval is a range about a given estimator that has a specified probability of containing the result of a complete enumeration of the sampling frame conducted under the same survey conditions. Associated with each interval is a percentage of confidence, which is interpreted as follows. If, for each possible sample, an estimate of a population parameter and its approximate standard error were obtained, then for approximately 90 percent of the possible samples, the interval from 1.645 standard errors below to 1.645 standard errors above the estimate would include the result as obtained from a complete enumeration of the sampling frame conducted under the same survey conditions. Appendix B discusses data reliability in more detail.