目标 1=B1+B2X2+1 Y =B+B,X+u 有必要假定干扰项的概率分布 2021/220 Hongfeng Peng Department of Finance, wuhan Univers ity2021/2/20 Hongfeng Peng Department of Finance, Wuhan University 3 目 标 Y X u i i i = + +   1 2 1 2 ˆ ˆ ˆ Y X u i i i = + +   有必要假定干扰项的概率分布！