Abstract: In this study, we conduct a Stated Choice Experiment (SCE) using eye-tracking technology to investigate if eye movements during the completion of choice sets reveal information about response uncertainty. We hypothesise that the number of times a respondent’s eyes switch focus between the alternatives in a choice set reflects the respondent’s choice uncertainty. Based on one of the largest samples of eye-tracking data in a SCE survey to date, we find evidence in favor of our hypothesis. We also link eye-tracking observations to model-based choice uncertainty – as expressed in the unobserved variance – through parameterization of the scale function in a random parameters logit model. We find that choices characterized by more frequent switching do indeed exhibit a higher degree of unobserved variance. While improving model fit, the Willingness to Pay (WTP) estimates and confidence intervals for the attributes are not significantly different in models where variations in scale due to uncertainty is adjusted for compared to a benchmark model. Overall, findings suggest that eye-tracking can provide an observable and exogenous variable for respondent uncertainty, potentially improving the handling of respondent uncertainty and thus the performance of the choice models in SCE studies.
Keywords:
- Eye-Tracking
- Respondent uncertainty
- Scale function
- Choice modelling
