predict u , residual
gen usq=u^2
gen lnusq = ln(usq)
reg lnusq X1 X2 X3 X4
predict g
gen h = exp(g)
gen y=Y/sqrt(h)
gen x5=1/sqrt(h)
gen x1= X1/sqrt(h)
gen x2=X2/sqrt(h)
gen x3=X3/sqrt(h)
gen x4=X4/sqrt(h)
reg y v x1 x2 x3 x4 , noconstant
你好,我想问一下,这个修正异方差的代码里为什么多了一个X5,这个X5代表了什么变量,为什么要过原点回归?
谢谢!