Methods Subjects were collected from community population by stratified multi-stage cluster sampling method. The data gathered from case investigation and serological detection.
方法对社区人群采用多阶段分层整群随机抽样方法抽取研究对象，进行个案调查和血清学检测。
Methods: the breakfast structure and the nutrition knowledge of 3 547 students in rural boarding middle school in Chongqing were investigated by adopting stratified two-stage cluster sampling method.
方法：采用分层二阶段整群抽样方法，对重庆市3 547名中学生早餐饮食结构和营养知识进行调查。
Methods. The survey was conducted according to multi-stage stratified cluster sampling method.
方法：分阶段分层整群随机抽样调查。
应用推荐