The Efficacy of Seven Hypothetical Bias Mitigation Methods

Hypothetical Bias is the difference between hypothetical and real behaviors, a central issue of convergent validity in stated preference methods. Numerous methods have been developed to mitigate hypothetical bias. We test seven such ex-ante, simul, and ex-post methods: Honest priming, cheap talk, oath, repeated opt-out reminder, default, unsure, and certainty follow-up and compare these outcomes to a hypothetical-control and incentivized treatment. We find that certainty follow-up successfully eliminates hypothetical bias. Default shows some success in reducing HB though does not eliminate it. All other methods show much more limited success at reducing HB.