Mode comparison study on willingness to buy and willingness to pay for organic foods: paper-and-pencil versus computerized questionnaire

摘要

This contribution looks into the survey mode effect using a randomized trial comparing data from paper-and-pencil and computerized web questionnaire concerning the willingness to buy (WTB) and the willingness to pay (WTP) for two food products certified as organic. A survey questionnaire was filled in by 110 university students for each mode in thermal comfort lab conditions. The design enables to study measurement variance specifically attributable to the mode of questionnaire completion (i.e. mode effect) and presentation of products (i.e. stimulus effect). While the two questionnaires were as similar as possible, the paper-and-pencil version involved the actual presentation of a tetra pack package of organic orange juice of 750 ml and a paper package of organic spaghetti of 500 g, but the computerized version involved their video projection. As regards the difference in substantive results, the prospective consumers "subjects" seemed to be more willing to buy the organic orange juice when presented live than presented on video embedded in the computerized questionnaire, while only women were willing to pay more for orange juice for the paper-and-pencil mode. No difference was found for the organic spaghetti product. As regards the response quality, in contrast to previous studies respondents wrote fewer words to the open-ended question in the computerized than in the paper-and-pencil version of the questionnaire. In addition, the study shows that using video clips as replacement for physical product presentations when measuring WTB and WTP as important concepts in consumer preference research needs further testing and evaluation as respondents may not react to them in the same way.