Did Oprah Winfrey's May 2007 endorsement of Sen. Barack Obama, D-Illinois, mean anything?

Talking heads may pooh-pooh celebrity endorsements, but Oprah, as we know, is no ordinary celebrity.

In the 12 weeks before she put Anna Karenina on her Book Club list in 2004, 11,648 units of the book were sold. In the twelve weeks after she deemed the Tolstoy classic merited inclusion, sales increased 5,421 percent, selling 643,122 units.

Before Oprah put Ciao Bella blood orange sorbet on her 2007 “Oprah’s Favorites” list the company website received an average of 175,000 hits a week. After the sorbet was put on the list, that number jumped to three million.

And then of course there was the fallout after Oprah devoted a show to "mad cow" disease in April 1996 and said that a guest's comments "just stopped me cold from eating another burger." Cattle futures fell 10 percent the next day and a group of cattle ranchers eventually -- unsuccessfully -- sued her for defamation,  seeking $11 million in losses.

Now two University of Maryland economists, Craig Garthwaite and Tim Moore, have attempted to quantify what Oprah meant to Mr. Obama.

In their study -- which includes all sorts of equations and variables and such -- they conclude that "her endorsement had a positive effect on the votes Obama received, increased the overall voter participation rate, and increased the number of contributions received by Obama."

They even come up with a number: 1,015,559.

As in, Oprah's endorsement meant 1,015,559 additional votes for Sen. Obama.

The authors did wonder if a similar increase in votes for former Arkansas Gov. Mike Huckabee could be discerned in areas where Chuck Norris was particularly popular, but they concluded that "Winfrey is a celebrity of nearly unparalleled popularity."

- jpt