This paper examines the driver demographics, driver travel characteristics, and driver adherence to survey protocol considerations that affect the likelihood of underreporting in a household travel survey. The research considers both the likelihood of vehicle driver trip underreporting and the level of vehicle driver trip underreporting by using a joint binary choice-ordered response discrete model. The empirical analysis uses the Global Positioning System-equipped sample of households from the 2004 Kansas City (Kansas and Missouri) Household Travel Survey which also provided travel diary information. The empirical results provide important insights about underreporting tendencies in household travel surveys. In particular, adults younger than 30 years of age; men; individuals with less than a high school education; unemployed individuals; individuals working in clerical and manufacturing professions; workers employed at residential land uses; individuals who make many trips, travel long distances, and trip chain; and respondents who fail to use a travel diary to log their travel before telephone retrieval of their patterns are associated with more underreporting. The underlying factors that influence whether an individual underreports are different from the factors that affect the level of underreporting.
