What Do All Those Endorsements Mean?

Barack Obama has Oprah Winfrey and Larry David on his side while Hillary Clinton is backed by Jack Nicholson and Barbara Streisand.

Presidential candidates don't only campaign hard for our votes but for the endorsements of influentials -- the people who can theoretically sway the preferences of a large number of voters.

On the surface, endorsements don't seem to have much influence on the outcome of races. Remember Al Gore's support for Howard Dean in 2004?

But political science researchers at UCLA claim that they have found a connection between public endorsements and the success of presidential campaigns:

"...in the period 1980 to 2004, the endorsements of party insiders drove the presidential nominating process."

Economists are divided about the value of endorsements. Depending on whether voters act in their own interest or are easily swayed by outsider opinions, endorsements and other types of political influence like advertisements can either improve or reduce welfare.

But there isn't much debate about what it is that endorsements are meant to do, economically speaking: give the influentials a reasonably easy way of conveying private information about a candidate.

If you're a person with persuasionary powers, it's much simpler to announce your preference for a candidate than to go person-by-person or group-by-group to get the message across.

Most endorsements, however, don't convey much hidden information because they're made by people who only have limited access to candidates. Does Barbara Streisand really know any more than the average well-informed voter about Hillary Clinton?

So who might know more? Perhaps their coworkers.

For example, Republican presidential candidate John McCain's colleagues on Capitol Hill seem to like working with him -- nine senators have endorsed his campaign.

What's more interesting is the Democratic side, where both Clinton and Obama have worked side-by-side for the past two years and have been competing for the support of their colleagues. It might be that Clinton, who has served for six years longer than Obama, has had more time to form relationships, or it might be that she's seen as someone who is easier to work with, but the New York senator has the support of 12 senators while Obama only has seven.