Using Internet in Stated Preference Surveys : A Review and Comparison of Survey Modes

Internet is quickly becoming the survey mode of choice for stated preference (SP) surveys in environmental economics. However, this choice is being made with relatively little consideration of its potential influence on survey results. This paper reviews the theory and emerging evidence of mode effects in the survey methodology and SP literatures, summarizes the findings, and points out implications for Internet SP practice and research. The SP studies that compare Internet with other modes do generally not find substantial difference. The majority of welfare estimates are equal; or somewhat lower for the Internet surveys. Further, there is no clear evidence of substantially lower quality or validity of Internet responses. However, the degree of experimental control is often low in comparative studies across survey modes, and they often confound measurement and sample composition effects. Internet offers a huge potential for experimentation and innovation in SP research, but when used to derive reliable welfare estimates for policy assessment, issues like representation and non-response bias for different Internet panels should receive more attention