对象与方法：研究对象采取分层整群随机抽样的方法，在大连市4所高校大一、大四年级学生中发放问卷800份，收回有效问卷726份。
Methods: By using questionnaires with multistage stratified random cluster sampling method, 726 valid questionnaires of 800 were backed from the university students in 4 universities in Dalian city.
方法对安徽省四县市的12岁及15岁儿童的龋病发病情况进行抽样调查，采用分层、不等比、多阶段整群抽样的方法。
Methods The survey of prevalence of dental caries in group aged 12 and 15 years in Anhui province was conducted using the non-proportional, stratified, cluster sampling method.
第四章陈述本文所从事的研究，介绍研究方法、目标、工具和所抽样例的原则与过程。
Chapter Four gives an account of the current study on teacher-initiated portfolios. It describes methodology in terms of objectives, sample portfolios and instruments.
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