Methods: The stratified sampling and cluster random sampling methods are used in this survey.
方法：本研究采用分层随机抽样方法和整群随机抽样方法。
Methods a questionnaire survey was conducted among the clinical doctors selected by stratified cluster random sampling from grade 1, 2 and 3 hospitals in Guangzhou.
方法采用分层整群随机抽样方法，询问调查抽中的广州市1级、2级和3级医院的一线临床医生。
Methods Stratified cluster random sampling was carried out in prevalence survey and questionnaires was applied.
方法采取分层整群随机抽样方法进行问卷调查。
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