variance for stratified sampling分层: lamination; layering; strati ...抽样: sample; sampling; specimen; ...分层抽样协方差: covariance for stratified sampling分层抽样的相对方差: relative-variance for stratified sampling分层抽样法: stratified sampling method下载手机词典可随时随地查词查翻译关注微信公众号：chachacidian，回复:分层抽样方差，即可在微信中查询翻译
