The three networks aired more than 36 minutes of commercials, including promotional announcements and public service announcements, during the DNC — compared with just 13 minutes of commercials during the GOP convention, according to Nielsen.

Of the three networks, CBS aired the most advertising during both conventions.

John McCain’s campaign ran 74% more ads during the Republican convention (11,845) than during the Democratic National Convention (6,791).  In contrast, Barack Obama’s campaign maintained consistent levels of advertising during both conventions (10,756 during the Democratic convention; 10,468 during the GOP convention).

Both parties’ committees ran more advertising during the opposing party’s convention than during their own.  The Republican National Committee Campaign ran 1,787 commercials during the Democratic Convention, but only 442 during the Republican Convention, while the Democratic National Committee Campaign aired 2,553 ads during the Republican Convention, but only 2,046 during the Democratic Convention. 

Political organizations, including “527” groups, ran approximately the same number of ads during both conventions: 22,245 spots during the Democratic convention and 25,767 during the GOP convention.

“Engagement” refers to the amount of attention paid to a television program by the average viewer.  Nielsen measures TV engagement by questioning a representative panel of viewers about their recall of specific telecasts’ content.

John McCain’s acceptance speech on September 4 drew the most attentive audience of uncommitted viewers, Nielsen reported.  Telecasts of Barack Obama’s and Sarah Palin’s acceptance speeches on August 28 and September 3, respectively, tied in second place as the second most engaging telecasts among uncommitted viewers.

Overall, viewers were more engaged by the telecasts of the RNC vs. the DNC.  Registered voters were 10% more engaged by the RNC than the DNC, while likely voters were 12% more engaged in RNC viewing. 

Male viewers were among the most attentive RNC viewers (15% higher engagement with RNC than DNC), as were older viewers, ages 35 and older, who were 13% more engaged by the RNC than the DNC. 

In contrast, younger viewers, ages 18 to 34, were 13% more engaged by the DNC, as compared with the RNC.

Read coverage of Nielsen’s findings in The Boston Globe and The Huffington Post.

Nearly two-thirds of all U.S. households (64.5%) — 120.1 million people age two or older — watched at least one of the 2008 political conventions, according to a new analysis released Thursday by Nielsen. 

Viewership levels for the Democratic and Republican conventions were essentially even, with about half of all U.S. households watching each.  Overall, 15% of all homes tuned in to the Republican National Convention only, while 15.7% tuned in to just the Democratic National Convention.  Another 33.9% of all households tuned in to both conventions.

Homes that watched both conventions were likely to be older (age 65+) and better educated (32.3% had college degrees) than viewers who watched only one of the conventions. 

RNC-only households were usually bigger (four people or more), had higher incomes ($100,000+), and were more likely to be white, while DNC-only households were smaller (two people), less wealthy ($20,000 or less), and more likely to be African American.

One-fifth (21.2%) of DNC-only homes were headed by an African American, while 83.5% of RNC-only homes were headed someone who is white.

Similar percentages of African American and white viewers tuned in to both conventions (35.7% and 34.5%, respectively).  Among African Americans, 27.4% watched only the DNC, and only 8.1% watched only the RNC.  Meanwhile, 16.2% of white viewers watched the RNC only, and 13.6% watched the DNC only.

Read the full report — and stay tuned during the presidential debates for more Nielsen TV audience analyses.

Read coverage of Nielsen’s findings in the Baltimore Sun, The Boston Globe, Broadcasting & Cable, and Multichannel News.

Online Buzz
An analysis by Nielsen of the online discussions around more than 30 speakers at the Democratic and Republican conventions showed Obama leading McCain, followed by Palin and Sen. Hillary Clinton.  Vice-presidential candidate, Sen. Joe Biden, rounded out the top five most buzzworthy politicians.

Online Traffic
Web traffic to BarackObama.com increased 32% during the week of the Democratic National Convention.  During the same period, traffic to McCain’s website increased 242%, perhaps driven by the announcement, late in the week, of Sarah Palin as his running mate.

Still, traffic to Obama’s site outpaced traffic to McCain’s site by a two-to-one ratio in the week ending August 31.

Online Advertising
John McCain’s campaign increased its online advertising in August, with image-based impressions up by 254% month-over-month and sponsored search links up by 43%.

Barack Obama’s campaign placed fewer online ad impressions during the same time period, reducing image-based impressions by 48% and sponsored links by 18%.

View the full media alert.

Read coverage of Nielsen’s findings in TV Week, The Boston Globe, Condé Nast Portfolio, and Silicon Alley Insider.