<p>Travel diary is one of the fundamental methods for collecting data critical for transportation planning, demand modelling, and analyses. Self-reported household travel surveys are known for recall and proxy biases. Both biases lead to underreporting of travel demand in the dataset. On the other hand, travel diaries collected through GPS-based methods are exempted from recall and proxy biases. This study investigates recall and proxy bias in self-reported travel surveys under the core-satellite design paradigm of urban passenger travel surveys. The study uses the Transportation Tomorrow survey (TTS) in the Greater Toronto and Hamilton area (GTHA) as the core dataset. The satellite survey is a GPS-based weeklong survey. The direct comparison between the core and satellite surveys shows that respondents who participated in both the TTS and the GPS survey demonstrated less biased diary reporting in the self-reported core survey. However, significant recall and proxy bias are identified for individuals who directly participate in the TTS but refuse to participate in the GPS survey and the proxy respondents in the TTS. Then, this study also found that respondents’ estimated willingness-to-participate in satellite surveys is positively correlated with their trip rates reported in the core survey.</p>