Our institute had completed the previous study on chronic pain prevalence successfully and we are experienced in conducting this type of study. The POP of the University of Hong Kong is experienced in conducting similar survey and questionnaire interviews. They have the manpower and training for the interview of this study. The questionnaire will be delivered by trained interviewers from their department. An experienced research assistant is mandatory in analysis of the data by comparing the change of outcomes in two time points, drafting the reports, coordinating the study, following up the program, retrieving data in 2002, which can give valuable information on the change.