Poynter's E-Media Tidbits mentioned a month ago how polls on news Web sites are inaccurate and are meant just for fun.
Yes, there's much that can be improved about them. Particularly on sites that have implemented mandatory registration.
The Chicago Tribune, for instance, requires readers to register an account in order to vote in polls (example poll). And it requires each registered user to have a valid e-mail address not used by any other user. But you can vote as many times as you want -- as long as you clear the appropriate cookie between votes.
The case appears to be the same on AJC.com, the Atlanta Journal-Constitution's Web site. (Disclaimer: I once worked there.) On a story with a related poll (example story), you can vote as many times as you want, as long as you clear cookies. And you have to be a registered user to be able to vote.
This is inefficient. Why not tie the two systems together, so that a registered user can only vote once?
Everyone would win. The quality of poll results would increase (although it would still be non-scientific), and registered users would have an incentive -- albeit a small one, but these things add up -- not to share their account information.
If you're going to require people to register to vote in a poll, you might as well tie their vote to their registration.