NASHVILLE, Tenn. -- With one week until Election Day, the race for mayor has never been tighter, according to local polling information.

Special Section: 2007 Mayoral Race

But are the polls accurate? Also, why do different polls have different results?

Why do they sometimes work, and why do they sometimes turn out wrong when the election occurs?

When the Channel 4 mayoral poll showed Karl Dean had pulled ahead of Bob Clement, it caught the attention of Nashville residents.

However, a City Paper poll claims Clement is slightly ahead but is virtually in a three-way tie with Howard Gentry and Karl Dean.

Vanderbilt poll expert Christian Grose said both polls are probably accurate.

“It's just that people don't have well-formed opinions in a lot of these races. The mayoral race is like that -- it’s in flux. People aren’t sure who they support,” Grose said.

Mayor Bill Purcell said if the polls were right when he ran, he would have never been mayor.

“For a candidate or a person who is trying to assess public opinion, it may be of some value. But a poll, frankly, to the rest of the world means very little and has a lot of opportunity to mislead people,” Purcell said.

People who are polled haven't voted yet, and polls also talk to a lot of people who don’t plan to vote.

So, if one of the trailing candidates does a better job of getting their voters out and front-runners' voters stay home, the race could change dramatically.

When the 4 percent margin of error is brought into the equation, it’s possible that Buck Dozier could be leading.

Even David Briley, who is last in all polls, is close enough with the margin of error and voter turnout.

Then, there is the growing number of people who refuse to answer any phone surveys, so their vote is a mystery.

Voters should not throw out the polls,though, because they can be accurate.

Polls in the tight Bob Corker vs. Harold Ford race for U.S. Senate said it was 51 percent to 48 percent in favor of Corker just before the election, and that turned out to be Corker’s margin of victory.

There are also poll numbers the candidates release themselves.

Groce said voters should ignore those figures because traditionally candidates will weigh their own polls with people friendly to their camp, or they simply won't release the numbers if they are unfavorable.

Special Section: 2007 Mayoral Race