5. Heteroskedasticity Correction Suppose X=b+b1X1+…+bXk+E;(1) and var(e=of=of(x), x1=(X1,11…k),=1,…,m,andf>0 Then var vara f(X f(X) x)0/X )=a2,i=1…,n5. Heteroskedasticity Correction 1) Suppose (1) and Then Y = b b X b X + i i k ki i 0 1 1 + + +  2 2 1 1 var( ) ( ), ( , , ), 1, , , and 0 i i i i i i ki f X X X i n f    = = = =  X X 2 2 1 1 var( ) var( ) ( ) ( ) 1 ( ) , 1, , ( ) i i i i i i f f f i n f     = = = = X X X X