Hypothetical Bias in the SG and TTO

Area of Science:

• Health Economics
• Decision Science
• Psychology

Background:

• Health state utility measurements are crucial for health policy and medical decision-making.
• Standard gamble (SG) and time tradeoff (TTO) are common methods, typically using hypothetical questions.
• The potential for bias in hypothetical questions remains unexamined.

Purpose of the Study:

• To investigate whether incentivizing choices in SG and TTO measurements reduces hypothetical bias.
• To assess the impact of incentives on health state utility valuations.

Main Methods:

• Utilized the Bayesian truth serum (BTS) to incentivize choices in SG and TTO.
• Conducted two online experiments with Dutch students (n=498) and US general population (n=1,298).
• Introduced default bias in the US sample to maximize incentive effects.

Main Results:

• Incentives did not significantly alter individual choices or aggregate valuations in SG and TTO.
• Default bias affected TTO but not SG measurements.
• Results were consistent across both student and general population samples.

Conclusions:

• Incentives do not appear to introduce bias into SG and TTO health utility measurements.
• The findings support the continued use of hypothetical questions in health state utility assessment.
• Current practices in health policy decision-making are validated by these results.