I believe those indexes simply follow the polls and news of the day, and aren’t really a predictor of anything.
Recall what they looked like late in the afternoon/early evening on election night in 2004? lol
Basically Intrade cuts through the hype and tells you what is really going on. If the Democrats had actually grabbed momentum recently.. then it would of showed up on Intrade, but just the opposite happened the numbers have moved more negative against them, which means regardless of what they are saying on TV and elsewhere Democrats know in their heart that they are going to get their asses whooped.
I agree. The people betting on intrade have only the polls to look at to determine how to place their money. Those same polls we get every day. It is nothing more than a consolidation of polls displayed as a trend.