The target population of this survey was defined as the principals of all local secondary schools excluding the international schools. No sampling was required.

This study was conducted by self-administered paper questionnaire, returned by the principals via mail or fax. The data collection period started from 20 June and ended on 8 July, 2008. A total of 116 questionnaires were received via fax, but only 115 cases were considered valid. The response rate of this survey was 22.4%, with a standard error of sampling of no more than 4.1%, had it been a representative survey (Table 1).

Table 1. Contact information of the survey

Successful Cases	Distributed Questionnaires	Response rate*	Standard Error**
115	514	22.4%	4.1%

* Response rate is calculated as the number of successful cases divided by the number of distributed questionnaires.
** Calculated as if these are random sample surveys.

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