Methods: According to regionalism of Zhejiang Province, 2084 middle school students were sampled from 36 classes of 6 junior middle schools and 6 senior middle schools from 8 cities and towns.

• 方法：根据浙江省行政区域的划分，在8个城市的6所高中6所初中，用分层整群抽样方法选取初一到高三的36个班级共2084名学生。