use iraq3
nbreg terror lpop ldist lgdp if cl~=. & totlit~=. & muslim~=.
nbreg terror lpop ldist lgdp totlit cl perso musl if cl~=. & totlit~=. & muslim~=.
nbreg terror lpop ldist lgdp totlit cl perso musl imr if cl~=. & totlit~=. & muslim~=.