A.簡單隨機(jī)抽樣;分層抽樣;整群抽樣B.多階段抽樣;配額抽樣;整群抽樣C.多階段抽樣;分層抽樣;PPSD.簡單隨機(jī)抽樣;目標(biāo)抽樣;PPS
A.Experimental StudiesB.Empirical StudiesC.PositivismD.Survey Research