7. February 2008 by emeris.

“If I fight on in my campaign, all the way to the convention, I would forestall the launch of a national campaign and make it more likely that Senator Clinton or Obama would win. And in this time of war, I simply cannot let my campaign, be a part of aiding a surrender to terror,” Romney told the Conservative Political Action Conference in Washington.”

http://obsidianwings.blogs.com/obsidian_wings/2008/02/romney-out.htm

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7. February 2008 by emeris.

In my last post I refered to information cascades with out really defining them.   They are a form of collective behavior where each member of a group asynchronously making the same decision.   Each member of the group had private information known only to them and public information from the observation of how other members of the group have decided.   Each individual makes their decision based on their private information and the available public information combined in some way.    Because of this dynamic the consensus decision of the group will not necessarily be the same as the decision that would be reached if all private information.

A toy example of this is consider a group of people making a binary decision, up or down, who all have private information that says to choose down except for some very small subset.  Let the aggregation method be majority rule of the private information and last two decision taken.  If we assume that two of the people with the minority information for first and both decide up, then the third person will see two ups (from the public information) and one down (from private) and also choose up.  The same for the fourth and later people as well, thus the group will all choose up, even though a majority of the private information says to choose down.   One such example is choosing forks at a fancy place setting.  It is clear that this is a toy model and there are much more sophisticated  systems, however this displays the important behavior.

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