(Dark Blue (280): Obama +7.0% or more
Lean Blue (58): Obama +2.6%-+6.9%
White / Toss-up (31): Obama +2.5% to McCain +2.5%
Lean Red (26): McCain +2.6%-+6.9%
Dark Red (143): McCain +7.0% or more)
Only 23 days left, and Obama's lead is still secure. Importantly, he is at 280 "solid" electoral votes, which means he leads states worth 280 electoral votes by 7.0% or more.
Why is 7.0% an important number? According to a study I performed back in June that tested the methodlology I am currently using, a look at the 42 Senate, Governor and Presidential swing state campaigns decided by 10.0% or less since 2004 revealed that no final-week polling average had ever been off by more than 7.0%. In fact, only one average was off by more than 5.75% (the 2004 Kentucky Senate race), and only four were off by more than 4.2%. So, when a simple, statewide polling mean in a general election shows someone ahead by 7.0% or more, you can take it to the bank. A lead of this size will always hold up on Election Day.
The reason I choose 2.5% as the cut-off point for states to be either "Leaning" toward one party or to be "Toss-ups," is that the study showed that only 11 of the 42 elections in question had polling averages that were off by more than 2.5%. Since the error could turn in either direction, a lead of 2.6% or more indicates a 73 in 84 chance of victory, or roughly 85%. So, it is a good shot, but not a complete lock. The average error in the study was 2.0%, indicating that a state is still a toss-up at a margin of 2.0%.
I point this out to indicate just how solid Obama's lead is right now. With 280 electoral votes at 7.3% or greater, I would estimate his chances at victory to be well over 99%. State by state details in the extended entry.
* Maine's four electoral votes are awarded as follows: two for the statewide winner, and one for the winner of each congressional district. ME-01 is about 3.2% more Democratic than the state as a whole, while ME-02 is about 3.2% less Democratic than the state as a whole.
** Nebraska's five electoral votes are awarded as follows: two for the statewide winner, and one for the winner of each congressional district. NE-01 is about 6.0% more Democratic than the state as a whole, NE-02 is about 11.0% more Democratic than the state as a whole, and NE-03 is about 18.0% less Democratic than the state as a whole.
Methodology The forecast is updated whenever there are enough new polls to warrant an update. The methodology for the forecast is simple and straightforward.
For each state, all polls with the majority of their interviews condcuted within the last 7 days from publication of the forecast are included in the averages. There are some necessary exceptions to this rule.
Every state has at least three polls, so the first exception are states without three polls that meet the previous criteria. In the event that three polls taken within the past week are not available, the three most recent polls are used. (Note: "Most recent" is determined by the mid-point in the dates of the polls. For example, a poll taken from 9/15-9/17 has a mid-pint of 9/16. In the event that more than one poll shares the most recent mid-point (within 0.5), all polls with that mid-point are included in the average.)
The second exception comes with polling firms that have conducted more than two poll in a state over the last 7 days. Every polling firm only has one poll per average.
No polling firm discrimination whatsoever. Polls are never excluded because the organization has a bad or partisan reputation.
No pre-September polls. I'm just sick of including them.
During the final two weeks of the election, only polls taken entirely within the past seven days will be included in the averages (with the same exceptions listed above, of course).
