Finally I have something new to report on Barack Obama:
Prior to the 2008 Democratic Presidential Primary, Barack Obama was endorsed by Oprah Winfrey, a celebrity with a proven track record of influencing her fans’ commercial decisions. In this paper, we use geographic differences in subscriptions to O! – The Oprah Magazine and the sale of books Winfrey recommended as part of Oprah’s Book Club to assess whether her endorsement affected the Primary outcomes. We find 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. No connection is found between the measures of Oprah’s influence and Obama’s success in previous elections, nor with underlying local political preferences. Our results suggest that Winfrey’s endorsement was responsible for approximately additional 1,000,000 votes for Obama.
That is work by Craig Garthwaite and Tim Moore and here is the full paper.