Measuring Personal Travel and Goods Movement A Review of the Bureau of Transportation Statistics' Surveys -- Special Report 277 (2003) / Chapter Skim
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A Letter Report on the National Household Travel Survey
A Letter Report on the National Household Travel Survey
Pages 54-78
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From page 54... ...
The committee has been charged with reviewing the current BTS sur vey programs in light of transportation data needs for policy planning and research and in light of the characteristics and functions of an effec tive statistical agency.2 This letter presents the committee's consensus findings and recommendations concerning the National Household Travel Survey (NHTS)
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From page 55... ...
Nevertheless, the committee identified opportunities for the agency to improve its personal travel surveys in terms of both their value to a wide range of users and the quality of the data pro vided. In particular, the committee recommends that BTS consider developing a family of personal travel surveys aimed at meeting the needs of a variety of users.
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From page 56... ...
The add-on surveys are gathering data from an addi tional 40,000 households using the same methodology and instruments 5 At the time of writing, the design of the 2001 NHTS has been finalized, and data collection is on going. Therefore the committee's recommendations address future versions of the NHTS (and other personal travel surveys)
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From page 57... ...
Integration of the ATS and NPTS was recommended as a means of pro viding "useful data for federal, state, and MPO analysis and planning pur poses, including consistent estimates of daily and long-distance household travel patterns, in a more cost-effective manner than two separate surveys, 7 According to a recent article on standardizing household travel surveys (NCHRP 2002, 1) , the wide diversity in design, application, and analysis of these surveys makes it difficult, if not impos sible, to compare results between one survey and another.
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From page 58... ...
These designs were selected to assess both the feasibility of using a combined survey instrument for daily and long-distance travel and methods for improving response rates. Although a combined data set for long-distance and daily travel should facilitate in-depth analysis of overall travel patterns, there were concerns that the burden placed on households participating in the survey could result in a loss of data quality.
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From page 59... ...
Recalling and re porting on these trips involve a major effort on the part of respondents, and there is some evidence that overall response rates decrease as a result of greater respondent burden. Consequently, some survey experts be lieve that household travel surveys have reached or surpassed their most cost-effective length (TRB 1996)
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From page 60... ...
The changing characteristics of telephone usage are reducing the effec tiveness of current telephone survey methods and may be introducing bias. Coverage and response rates are declining for the following reasons: · Consumer resistance: Unsolicited phone calls, especially telemarketing calls, compete for respondents' attention and have a negative effect on response rates.
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From page 61... ...
Overall response rates varied from 10 to 75 percent, with a mean of 36.4 percent. In response to a ques tion from the committee, one survey expert noted that response rates for personal travel surveys are generally in the high 50 percent range for recruitment interviews and on the order of 70 to 75 percent for extended data-gathering interviews, giving overall response rates in the high 30 per cent to low 40 percent range.17 The overall response rate for the 1995 NPTS was 37.2 percent (51.6 per cent for the recruitment interview and 72.1 percent for the extended data-gathering interview)
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From page 62... ...
· Data collection methods: The 1995 NPTS used restrictive data collec tion methods to improve data quality over that obtained in the 1990 version of the survey. The definition of a "usable household" was rig orously constrained, a 6-day data collection window was applied, and the use of proxy reporting was limited.
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From page 63... ...
Although this anticipated overall response rate for the 2001 NHTS is rel atively high compared with response rates for household travel surveys conducted by MPOs across the United States (Stopher and Metcalf 1996) , it is low compared with the response rates for the 1995 ATS and for other federal policy-related surveys, as illustrated by two examples.
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From page 64... ...
BTS is aware of many of the factors contributing to nonresponse for the NHTS and has supported related research investigations. For example, BTS was one of the sponsors of the TRB Personal Travel Survey Round table.20 Participants in this meeting discussed survey methodology issues and identified problem areas and research needs relating to RDD method ology and low response rates.
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From page 65... ...
This training involves, among other items, scheduling call-back ap pointments for a person who is too busy to respond at the time the interviewer calls; alleviating respondent fears and concerns; leaving voice mail messages; overcoming language, speech, and hearing bar riers; and role playing to gain practice in handling a range of refusals, questions, and other situations. Westat has not conducted a formal evaluation of the effectiveness of this training but believes that the re sulting increased response rates vis-à-vis other similar travel surveys indicate its effectiveness.22 · Development of user-friendly survey materials: Representatives of BTS and FHWA reported that such materials should aim for a sixth-grade reading level and make use of graphics.
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From page 66... ...
26Larger MPOs that develop their own travel forecasting models tend to conduct their own travel surveys and use the NPTS/ATS data to benchmark and validate their results, whereas smaller MPOs with limited resources may rely on national data to calibrate their travel model parameters.
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From page 67... ...
Although the NPTS and ATS data do not provide statistically reliable in formation on personal travel in a specific location (e.g., Topeka, Kansas) , they do provide policy makers with a guiding sense of what is happening in settings with similar demographics (e.g., locations with similar popu lation densities and average household incomes)
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From page 68... ...
The members of this committee are high-level managers and researchers, some of whom are not primary data users but may receive reports and analyses ultimately traceable to BTS data. RECOMMENDATIONS Recommendation 1 BTS should consider developing a family of personal travel surveys aimed at meeting the needs of a variety of users.
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From page 69... ...
Low response rates in household travel surveys are attributable to a variety of factors, including the complexity of such surveys, the grow ing resistance to surveys in general and telephone surveys in particular, and the changing patterns of communications access to American households. Furthermore, the diversity of analysis and decision needs to be met by BTS's national travel surveys suggests that it may become increasingly difficult to meet user requirements for both quality and subject coverage with a single, periodic national household travel sur vey.28 Therefore, BTS should consider a variety of survey options for measuring personal travel and should not necessarily limit its efforts to a cross-sectional household travel survey conducted once every 5 years using CATI methods.
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From page 70... ...
A technical advisory committee to advise on issues such as survey design and research leading to improved methodologies. BTS should consult with a range of constituencies -- including those outside of the Washington, D.C., area -- as part of the development of its personal travel surveys.
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From page 71... ...
For example, reductions in the sample size can result in inadequate data to assess the travel behavior of specific groups within the population, such as minorities or low-income households. In some instances, random stratified sampling techniques may be helpful in capturing sufficient data on "rare" behaviors -- for example, trips involving walking, biking, or transit use -- to permit calibration of models.
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From page 72... ...
Therefore, BTS -- in consultation with its policy and technical advisory committees -- should consider using longitudinal panel surveys as a means of capturing information on behavioral dynamics. Such surveys could either supplement or replace traditional cross-sectional household travel surveys.29 Panel surveys can be essential for understanding location choices and moving behaviors, which have important influences on travel needs.
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From page 73... ...
Internet-based travel diaries also permit cost-efficient, high capacity survey data retrieval and can increase unit and item response rates and resulting data quality. However, the up-front design cost is rel atively high, and such diaries are susceptible to disruption by computer viruses and hackers.
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From page 74... ...
New Survey Methods and Techniques Given the shrinking response rates in personal travel surveys conducted using traditional telephone methods, BTS needs to invest immediately in research into new survey methods and techniques for implementation in 5 to 10 years' time. BTS and its user community have a vested interest in understanding the implications for survey research of trends in house hold structure, travel and activity patterns, and technologies, so that sur vey methods can be continuously adapted to ensure the availability of essential travel data.
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From page 75... ...
reducing nonresponse rates in general and (b) obtaining travel survey data from underrepresented groups, such as high-income households that travel extensively, non English speakers, teenagers, and large households.
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From page 76... ...
Nonetheless, ef forts to link contextual data to travel behavior and demographics must address two potentially conflicting requirements -- the retention of suf ficient geographic information for data to be useful and the suppression of any information that could undermine the confidentiality of individ ual households. Advances in network modeling and the expanded availability of pow erful computational resources should facilitate the linkage of contextual data to travel behavior and demographics, but remaining obstacles in clude limits on the availability of supply data and the absence of analysis tools for measuring service attributes as a function of respondent loca tion.
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From page 77... ...
1997. An Overview of Response Rates in the National Household Education Survey: 1991, 1993, 1995, and 1996.
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From page 78... ...
In Conference Proceedings 10: Conference on Household Travel Surveys: New Concepts and Research Needs, National Research Council, Washington, D.C., pp.
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