With the presidential nominating conventions now behind us, the nation is gearing up for the election's homestretch. Sold and scheduled are hundreds of millions of dollars' worth of television ads while get-out-the-vote operations have been launched in towns and cities across the country.

Coverage of the campaign has taken over the news media; with each new event or drama carrying with it significant implications for which candidate will win in November.

...Or so we are told.

Not true, says Christopher Wlezien, professor of political science at Temple University.

In his forthcoming book, The Timeline of Presidential Elections: How Campaigns do (and do not) matter (2012), Wlezien and co-author Robert Erikson of Columbia argue that specific events in a campaign matter much less than we think and certainly much less than it would appear based on the media attention they receive — not to mention the enormous amount of effort and money spent on them.

For the book, Wlezien examined data from nearly two thousand national polls covering every presidential election from 1952 to 2008 in order to develop an idea of how voters' preferences take shape over the course of a campaign.

He found that over the timeline of a presidential campaign the electorate's collective choice undergoes a slow "evolution." And, he says, "this evolution is predictable and based on fundamental factors, such as partisan predispositions, economic conditions and candidate attributes."

Polls from the beginning of the year, the authors show, rarely predict the election outcome. However, by mid-April after the candidates have been selected, voters start to make up their minds — and polls during this period in past years have successfully named the winner in 11 of 15  elections.

But, says Wlezien, a similar “evolution” takes place in the last six months. Instead of resulting in dramatic change, particular events during this period of a campaign — including debates — simply confirm voters' inclinations.

"Voters see things through their preference lenses, typically judging their favored candidate to be the winner of a debate," he said.

Given an electorate that is as polarized as it is this year, the impact of the 2012 debates might be particularly hard to find," said Wlezein.

According to Wlezien, the most consequential events of the campaign are the conventions. "They focus voters’ attention on the election and often substantially rearrange their preferences. Most importantly, unlike other campaign events, the effects of conventions can last to impact the Election Day outcome,” he said.

“Conventions really are collections of many events, the most important of which are the presidential candidates’ speeches. These allow the contenders to present themselves and define their positions, and they attract the greatest media attention and have the biggest impact on voters," he said.

"After the conventions, electoral preferences harden," said Wlezien. "History shows that the leader in the polls at the onset of the fall campaign almost certainly will be the victor," he added.

In the end, Wlezien and Ericksen conclude that it's the fundamentals that matter — but only because of the campaigns.

"Through campaigns, voters are made aware of — or not made aware of — fundamental factors like candidates’ policy positions that determine which ticket will get their votes," Wlezien said.