“We have never weighted polls by party affiliation” - Frank Newport, Editor in Chief of Gallup.
Party affiliation follows the way a person is currently inclined to vote and party affiliation doesn’t drive how someone votes.
“We only ask the person after we have polled them who they currently self-identify with at the end of the poll for informational purposes.”
See here:
http://www.freerepublic.com/focus/f-news/2948176/posts?page=1
Somebody explain to me how such a methodology is better and more accurate than the others.
Weighing by party affiliation is an excellent way of confirming the validity of your sampling technique. The problem is that party registration is verifiable, party affiliation is not.