Impact of multiple sample frames on data quality of household travel surveys: the case of the 2016 Transportation Tomorrow Survey

The landline sample frame has been the method for recruiting participants for household travel surveys for many years. However, more recently, the representativeness of populations has declined with the reduction of household landline use and the rise of cellphone use. As a result, interest has turned to construct the survey sample frame using multiple lists. To attempt to alleviate underrepresentation, the 2016 iteration of the Transportation Tomorrow Survey (TTS) – the regional household travel survey of the Greater Golden Horseshoe located in southern Ontario, Canada – used multiple sample frames consisting of address/phone, address-only, and phone-only lists. To analyze the impact of a multi-frame approach, sample frames are compared based on demographic and trip variables to investigate whether there are significant differences between sample frames. Trip variable analysis via chi-squared and interaction effects modeling show small but significant differences, particularly between address-only and address/phone frames. The multiple sample frame is shown to improve representation compared to the singular landline frame; however, some broad representation issues remain with respect to age and household-size distributions, particularly in rural areas. This points to the need for alternative methods to recruit younger individuals and larger households.