Development of a bias ratio to examine factors influencing hypothetical bias

Using data from three contingent valuation studies, this study investigates if socio-economic factors and the type of good being valued can help explain changes in respondents' answers. A bias ratio, defined as the ratio of respondents who change their choice under hypothetical and " real" settings, is developed to help explain changes in respondents' answers. Marginal changes in the bias ratio resulting from a change in a particular independent variable consist of changes in responses in both the hypothetical and real situation. Results provide limited evidence that socio-economic variables and type of good being study can help in explaining bias. Respondents who are older, have a higher level of education, and are environmentally conscious tend to show less bias. Familiarity with the good also tend to decrease bias. A large amount of the variation in bias, however, remains unexplained.