Districts that registered higher levels of bias systematically produced more votes for Bush.

I find this conclusion overreaching, because it ignores the opposing candidate. For some of these highly biased voters, Bush may simply be the lesser of two evils. The voters may have been turned off by a common liberal or democratic policy that Al Gore or John Kerry or John Edwards said. It could be about anything -- affirmative action, gun control, school prayer, or gay rights, for example.

My criticism here falls under "correlation does not imply causation."

On this topic, I was pleasantly surprised to find that the Wikipedia article on the "correlation implies causation" fallacy uses one of my favorite Simpsons scenes as an example:

Homer: Not a bear in sight. The "Bear Patrol" is working like a charm!
Lisa: That's specious reasoning, Dad.
Homer: [uncomprehendingly] Thanks, honey.
Lisa: By your logic, I could claim that this rock keeps tigers away.
Homer: Hmm. How does it work?
Lisa: It doesn't work; it's just a stupid rock!
Homer: Uh-huh.
Lisa: But I don't see any tigers around, do you?
Homer: (pause) Lisa, I want to buy your rock.

These days, everyone has a rock for sale. What's yours?

RE: Study Ties Political Leanings to Hidden Biases