Declining survey response rates have increased the costs of travel survey recruitment. Recruiting respondents based on their expressed willingness to participate in future surveys, obtained from a preceding survey, is a potential solution but may exacerbate sample biases. In this study, we analyze the self-selection biases of survey respondents recruited from the 2017 U.S. National Household Travel Survey (NHTS), who had agreed to be contacted again for follow-up surveys. We apply a probit with sample selection (PSS) model to analyze (1) respondents’ willingness to participate in a follow-up survey (the selection model) and (2) their actual response behavior once contacted (the outcome model). Results verify the existence of self-selection biases, which are related to survey burden, sociodemographic characteristics, travel behavior, and item non-response to sensitive variables. We find that age, homeownership, and medical conditions have opposing effects on respondents’ willingness to participate and their actual survey participation. The PSS model is then validated using a hold-out sample and applied to the NHTS samples from various geographic regions to predict follow-up survey participation. Effect size indicators for differences between predicted and actual (population) distributions of select sociodemographic and travel-related variables suggest that the resulting samples may be most biased along age and education dimensions. Further, we summarized six model performance measures based on the PSS model structure. Overall, this study provides insight into self-selection biases in respondents recruited from preceding travel surveys. Model results can help researchers better understand and address such biases, while the nuanced application of various model measures lays a foundation for appropriate comparison across sample selection models.

调查回复率的下降增加了旅行调查招聘的成本。根据从先前调查中获得的参与未来调查的意愿来招募受访者是一种潜在的解决方案，但可能会加剧样本偏差。在这项研究中，我们分析了从 2017 年美国全国家庭旅行调查 (NHTS) 中招募的受访者的自我选择偏见，他们同意再次联系进行后续调查。我们应用带有样本选择（PSS）模型的概率来分析（1）受访者参与后续调查的意愿（选择模型）和（2）他们一旦接触后的实际反应行为（结果模型）。结果证实存在与调查负担、社会人口特征、旅行行为、和项目对敏感变量无反应。我们发现年龄、房屋所有权和医疗条件对受访者的参与意愿和他们的实际调查参与度有相反的影响。然后使用保留样本验证 PSS 模型，并将其应用于来自不同地理区域的 NHTS 样本，以预测后续调查的参与。选定社会人口和旅行相关变量的预测和实际（人口）分布之间差异的影响大小指标表明，所得样本可能在年龄和教育维度上存在最大偏差。此外，我们总结了基于 PSS 模型结构的六种模型性能度量。总体而言，这项研究深入了解了从之前的旅行调查中招募的受访者的自我选择偏见。