stratify
verb [ T ] uk/ˈstræt.ɪ.faɪ/ us/ˈstræt̬.ə.faɪ/
使分层；使成层；将…分组
to arrange the different parts of something in separate layers or groups
The sample of people questioned was drawn from the university's student register and stratified by age and gender. 调查问卷的抽样人群选自大学的学生名单，按年龄和性别分组。
a stratified society 分层的社会