Contrast group: Other 218 undergraduates were adopted in cluster sampling, taking class as unit.

对照组: 除外观察组学生,随机在4届学生中以班为单位整群抽样218名学生.

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Methods Cluster sampling and random sampling Methods: Were used to choose the subject.

方法采用整群随机抽样和单纯随机抽样方法确定调查对象.

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Methods 1589 third grade pupils sampled from 10 provinces and cities by stratified cluster sampling.

方法分层随机整群抽样,从10个省市中随机抽取小学三年级学生共1589人,填写结构式调查问卷.

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Methods: With stratified sampling and cluster sampling, we investigate 487 families in poverty.

方法采用分层整群抽样方法调查487户贫困家庭.

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This paper discusses cluster sampling and stratified cluster sampling in continuous surveys with censuses.

本文讨论了连续调查中应用普查方法时的整群抽样和分层整群抽样.

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