Methods a stratified samplingstudy on the epidemiological feature of fatty liver was conducted among 1992 workers from 4 factories of Ma 'anshan iron and steel general company.
方法采用分层整群抽样方法，抽取马钢公司四个工厂共1992名职工进行脂肪肝的流行病学调查。
3
Method:A cluster samplingstudy on the condition of injuries was conducted among 1059 rural inhabitants in a certain township in Tongjiang County, Sichuan province from Jan 1998~Jan 1999.