I have applied the following commands to winsorize but still the data is not normal
sum sizeofboard, detail
clonevar sizeofboard_w= sizeofboard
su sizeofboard_w, d
replace sizeofboard_w= r(p99) if sizeofboard_w>=r(p99)& sizeofboard_w<.
replace sizeofboard_w= r(p1) if sizeofboard_w<=r(p1)