Method A total of 4 882 undergraduates from 6 universities in Shanxi province was investigated with multistage stratified random cluster sampling.
方法采用多阶段分层随机整群抽样方法调查山西省普通高校一、二、三年级本专科大学生4 882名。
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Method Cochran's classic sampling theo- ries, the improved randomized response technique(RRT) model, total probability formulas and properties of variance were used in this paper.