Thu, 1 May 2014
You can't just poll voters, if you want to predict how voters will choose. You have to poll voters who will choose. If a voter isn't going to vote, that voter will not have much effect on an election.
It is hard to figure out who is going to vote. Some pollsters go by past elections, taking into account what percentage of different ages, races, income groups, and educational levels have voted. So, if you find you're over-representing left handed people with blue eyes, you just count their numbers less. It's called weighting.
But weighting depends on past patterns holding in the future. Patterns are getting tricky.
It's getting harder to figure out who is going to vote for another reason. Republicans have been taking steps to make it harder for minorities and college students and working class people to vote. At the same time, courts are beginning to take a harder look at voter suppression. So it's hard to predict who will have their voting rights taken away by conservatives.