In particular, the committee encourages BTS to explore opportunities that add value to the NHTS and CFS without involving major increases in survey cost. For example, it may be possible to assist users needing more detailed geographic data on freight movements by modifying the CFS such that national and local data sets can be readily combined.2 Similarly, revisions to the NHTS could help link data to the contextual information needed for policy analysis and model estimation. A recent National Research Council (NRC) report (Martin et al. 2001, 7) recommends that federal statistical agencies seek opportunities to integrate data from more than one survey or from other sources as part of the continuing development of more useful data, and the committee urges BTS to follow this advice. In particular, dialogue with users could address opportunities to coordinate data collection initiatives in an effort to obtain consistent and comparable local, state, and national data.

In developing and enhancing its flagship surveys, BTS will need to take account of user demands for both data consistency to support survey-to-survey trend analysis and expanded survey coverage to include evolving phenomena such as e-commerce. As noted in the letter report on the NHTS (Appendix A), changes in survey scope and design can result in additional complexity in trend analysis incorporating data from earlier surveys. Thus, BTS will need to develop a strategy to meet the potentially conflicting requirements for data consistency over time and expanded survey coverage.

Recommendation 2: BTS, together with its CFS and NHTS partners, should establish a formal process for (a) eliciting and responding to the needs of the community of data users on a regular basis and (b) consulting these users about key decisions affecting future surveys.

While information on the needs of data users does not guarantee good surveys, BTS cannot produce quality products without understanding these needs. Information on how and for what purposes data will be used is extremely important in developing an effective survey design.


A recent Transportation Research Board (TRB) report addresses approaches to ensuring compatibility between national freight data and supplemental state and local data sets (TRB 2003).

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