This research project compared the results from a public opinion survey about transportation taxes that was administered using two different survey modes, a national, random-digit-dial (RDD) telephone survey and an online survey with respondents recruited from a panel. There is considerable interest among survey researchers in using online survey panels as a replacement for RDD surveys. RDD surveys are becoming much more expensive to conduct, and researchers also worry that the quality of the results may be dropping because of rising refusal rates for phone surveys. However, a key question for researchers is to understand how a study’s results may differ depending on the survey mode.
The survey questionnaire tested for this study asked United States residents their views on various transportation tax and fee options available at the federal level, including questions specifically designed to assess public-transit-related spending. The revenue tools explored include raising the federal gas tax rate and replacing the gas tax with a mileage fee. In addition, the survey collected data on standard sociodemographic variables, a few travel-related characteristics, opinions about the transportation system, and knowledge about funding for public transit.
Comparing the results from the two survey modes reveals statistically significant differences both about who answered the survey as well as how respondents answered the questions. Responses were statistically significantly different by survey mode for most questions, with the magnitude of the differences often ten percentage points or more.
HILARY NIXON, PhD
Dr. Nixon is professor of Urban and Regional Planning at San José State University. Her research and teaching interests in environmental planning and policy focus on the relationship between environmental attitudes and behavior, particularly with respect to waste management and linkages between transportation and the environment. She holds a B.A. from the University of Rochester in Environmental Management and a PhD in Planning, Policy, and Design from the University of California, Irvine.
ASHA WEINSTEIN AGRAWAL, PhD
Dr. Agrawal is the Director of the MTI National Transportation Finance Center and also professor of Urban and Regional Planning at San José State University. Her research and teaching interests in transportation policy and planning include transportation finance, bicycle and pedestrian planning, and travel survey methods. She also works in the area of planning and transportation history. She has a BA from Harvard University in Folklore and Mythology, an MSc from the London School of Economics and Political Science in Urban and Regional Planning, and a PhD from the University of California, Berkeley, in City and Regional Planning.