Four and nine well-trained interviewers were employed, and 200 and 348
questionnaires were collected in Manila and Naga city, respectively. Interviewers visited
each household chosen randomly, explained the questionnaire and panels, asked
questions and wrote answers by themselves. The time they spent per questionnaire was
approximately 20 minutes. (We conducted Contingent Valuation Methods (CVM) as well
as Conjoint Analysis. See Ara (2002) for the results of CVM.) Six choice experiments
were asked to each respondent.