I want to reiterate something Nate Silver wrote last night: although Scott Brown is the favorite, he is by no means a 100% lock to win. This is the case across all forecasting models:
4%, 5%, 25%, 31%, 35%--none of these are great chance for Coakley, but they are still chances. This campaign has not reached the 10% range, at which point the odds of victory would be reduced to zero (at least in an election pitting a Democrat vs. a Republican).
- On Pollster.com, Charles Franklin looks at 18 forecasting models for the campaign, all of which show Brown ahead. However, a lead in a forecasting model, even across 18 forecasting models, is still not a lock.
Franklin says that the standard estimate for Pollster.com shows Brown ahead by 6.2% (although the chart at Pollster.com says 6.9%). In the 55 closest (under 17.0% estimate) statewide elections from 2008-2009, there were 5 instances where Pollster.com's standard Loess regression estimate missed the final results by more than 6.2%, and 4 instances where it was missed the final results by more than 6.9%. That would give Martha Coakley a 4% chance to win if the lead is 6.9%, and a 5% chance to win if the lead is 6.2%.
- On 538, Coakley is given a 25% chance to win, and Brown an estimated advantage of 2.2%. That squares with my estimate of Nate's error rate. Based on Nate's 2008 results and a deficit of 2.2%, Coakley would have a 24% chance to win.
- And finally, my model gives Coakley a 35% chance to win (although, in this specific case, I actually think it is less, around 31%, given the recent trendline).
Weather is bad, but turnout appears high anyway. Whether it is high in Brown areas or Coakley areas is anecdotal and not entirely clear, but Boston does have high turnout. The standard line has been that higher turnout helps Coakley.
Another point of hope for Coakley is that no polling was conducted yesterday. Brown's support is very new, and thus very soft. As such, it is possible there has been some movement back in her direction since Sunday night. Public opinion does not follow physical laws, and just because a candidate was trending upward does not mean that candidate will continue to trend upward.
My best estimate, based on the available data, is that Brown will win by between 0.9% and 2.7%. However, no matter which way you look at it, Coakley does still have a chance. Not a good chance, but a chance none the less.