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.
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.
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。
应用推荐