In our administrative survey, well trained professional interviewers were required. Interviewers
received extensive training by attending full-day sessions that emphasized the use of visual aids,
the need for neutrality, and the nature of the questionnaire. The survey instrument took an average
of 30 minutes to complete. Moreover, in the field survey, a supervisor was appointed for each
group to facilitate, check and recheck, and to assure the quality of the questionnaire. After
finishing interviews for each day, the research team held a meeting to summarize the results and
problems.