Assessing the impacts of alternative 'Opt-out' formats in choice experiment studies: Consumer preferences for genetically modified content and production information in food
2003
Kontoleon, A. (University of Cambridge (UK)) | Yabe, M.
SUMMARY An important aspect of the design of stated preference choice experiments concerns the inclusion and format of an opt-out option in the hypothetical choice set(s) presented to the respondent. This paper assessed the implications from using alternative 'opt-out' formats in choice experiment studies. Two alternative opt-out formats have been widely used, the 'do not buy' format and the 'buy/choose my current brand' format. The decision of which format to use in different cases may have a substantial impact on the estimated parameters and welfare measures derived from choice experiment data. These impacts are examined in a data set from a choice experiment study on consumer resistance to genetically modified content in foods. A split sample design was used in which the first treatment was provided with the option of 'not buying' the good at all while the second with an option of 'buying their usual brand'. Information over the actual purchasing habits of this latter group was collected and was incorporated into the estimation processes. The results from each treatment were separately analyzed and the impact of alternative opt-out formats on response patterns and on the significance and stability of coefficients across treatment groups was examined. In addition, using findings from the experimental psychology literature the possible behavioral and psychological forces that are at work under each treatment were assessed. Finally, certain methodological implications for the design of choice experiment studies are drawn.
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