Eight Key States, By The Numbers

By most reasonable estimates, Obama has 238 electoral votes firmly in his column, and McCain has 200.  The remaining 100 electoral votes are still in play.  These votes are found in the following eight states, all of which are within 3% according to 538.com's latest estimates:

Florida, 27 EV
Ohio, 20 EV
Michigan, 17 EV
Virginia, 13 EV
Colorado, 9 EV
New Mexico, 5 EV
Nevada, 5 EV
New Hampshire, 4 EV

Obama needs 32 of these 100 votes to win; 31 will result in a 269-269 electoral tie.

According to 538.com's latest estimates, Obama's probability of winning each of these states is as follows:

Florida, 28% (McCain leads by 3.0%)
Ohio, 33% (McCain leads by 2.2%)
Michigan, 64% (Obama leads by 1.8%)
Virginia, 30% (McCain leads by 2.8%)
Colorado, 45% (McCain leads by 0.6%)
New Mexico, 64% (Obama leads by 1.9%)
Nevada, 33% (McCain leads by 2.6%)
New Hampshire, 71% (Obama leads by 3.0%)

Obama is favored in three of these states, worth 26 electoral votes.  So, we're probably looking at a 264-274 loss, right?

Well, probably not.  Given eight states, there are 256 (2 to the eighth power) possible combinations of states carried by either candidate.  If we assume the states behave independently, we can calculate the joint probability of each of these combinations, and the sum of all combinations that give Obama at least 32 EVs can be taken as the likelihood of victory.

[Strictly speaking, the states probably don't behave independently.  If there are large shifts in the national numbers, the states will more more-or-less in unison.  But if the national numbers are relatively stable, independent behavior is a more reasonable assumption.]

Without further ado...

Obama wins 63.4% of the time.  He wins 203 of the 256 conbimations, but his total probability is lowered because his probabilities of winning individual states tend to be lower than McCain's.

McCain wins 31.9% of the time, 47 of 256 combinations.

The remaining 6 combinations, which collectively occur 4.7% of the time, result in a tie.

Obama's mean electoral vote count is 278.68 (238 + 40.68 of the 100 in play); his median is 277 (238 + 39 of the 100 in play).

Tags: electoral votes, probability (all tags)

Comments

8 Comments

Re: Eight Key States, By The Numbers

My take if the election were held today

McCain
Florida, 27 EV
Ohio, 20 EV
Virginia, 13 EV
New Mexico, 5 EV

Obama
Michigan, 17 EV
Colorado, 9 EV
Nevada, 5 EV
New Hampshire, 4 EV

Obama needs 32 of these 100 votes to win; 31 will result in a 269-269 electoral tie.

Its tight.

by dtaylor2 2008-09-11 01:43PM | 0 recs
Re: Wow

Obama is currently losing this election.

He would not lose today.

But his momentum is towards a lost election.

by dtaylor2 2008-09-11 02:47PM | 0 recs
Pennsylvania

A month ago Obama led McCain in PA by over 7pts (RCP average). Today his lead is slightly over 2pts. That's 21 EV which should be firmly in his column but which he's having to fight for... despite it being Biden's homestate (Scranton roots). I'm not trying to be a concern troll, but this is not good news.

The first debate (Sept 26) cannot come fast enough. We need a serious game changer.

http://www.realclearpolitics.com/epolls/ 2008/president/pa/pennsylvania_mccain_vs _obama-244.html

NYTimes web article today:


http://www.nytimes.com/2008/09/11/us/pol itics/11web2-seelye.html

Troubling Signs for Obama in Pennsylvania

Pennsylvania has voted for Democrats for president since 1992. But no one ever said winning it would be as easy for Senator Barack Obama as, say, ladling Cheez Whiz onto a Pat's steak.

In April he managed to insult the state's rural voters, saying they cling to their guns and religion because they are bitter about their economic plight. And he lost the primary to Senator Hillary Rodham Clinton.

Since winning the Democratic nomination, Mr. Obama's campaign has labored to secure his standing here. It has conducted a ferocious voter registration drive, flooded the airwaves with commercials and dispatched thousands of volunteers to knock on doors and make phone calls. It has opened 65 offices across the state -- four times as many as Mr. McCain has -- and more than it has opened in any other state.

Still, Craig Schirmer, the Obama state director, said on a conference call with reporters Wednesday that he expected the race here to be "incredibly close," within "a couple" of percentage points.

Maybe he was just lowering expectations.

But a new Quinnipiac poll released on Thursday shows that Mr. Obama's lead over Mr. McCain in Pennsylvania has shrunk to three percentage points (48-45) from seven percentage points on Aug. 26. (The sampling was taken Sept. 5-9 of 1,001 likely Pennsylvania voters with a margin of error of plus or minus three percentage points, making the results statistically a dead heat.)

Mr. McCain has narrowed the gap in Pennsylvania by wiping out Mr. Obama's lead among independent voters, said Clay F. Richards, assistant director of the Quinnipiac University Polling Institute. Mr. Obama still holds a three-point edge "by convincing previously uncommitted Hillary Clinton primary voters and Catholics to move into his camp -- the Catholics perhaps because of some help from running mate Joe Biden, a Catholic from Scranton," Mr. Richards said.

Mr. McCain has also gained ground among white women, according to this poll and others, perhaps reflecting a positive reaction to his choice of Gov. Sarah Palin of Alaska as his vice-presidential running mate.

-read the rest in the link-

by twinmom 2008-09-11 02:01PM | 0 recs
Interesting

Although McCain is favored in five states which would give him an electoral vote majority, the joint probability calculation gives Obama the higher probability of winning. This is very counterintuitive. It's kind of like if you've got 30 people in a room, chances are much greater than 50-50 that at least two people will share a birthday.

But there is some good news and bad news. The bad news is that Obama now trails in Michigan and Nevada. In addition, McCain is now within two points of Obama in Pennslyvania. The new polls suggest that McCain is now the odds on favorite to win.

The good news is that Democrats will have a majority congressional delegation in the majority of states. Thus, Obama will only need to have 269 electoral votes to win. Also, expectations for Palin is high and for Biden is low. If Palin does not do as well as expected in the debates, there could be a near uniform shift in the popular vote back to Obama.

by Zzyzzy 2008-09-11 02:04PM | 0 recs
269 equals President Biden??

If it ends up tied at 269 electoral vote the party with the  fewer states can refuse to vote in the house. A quorum of 2/3 of the states is required to vote by March 4th. After March 4 the VP becomes President. The Senate picks the VP and there is no quorum requirement or time limit.  Dems should pick up some Senate seats and can vote for Biden. But if they don't, then our old friend Joe Lieberman can pick the next President of the United States. Oh, the horse trading will be quite a sight to see.

by ineedalife 2008-09-11 04:17PM | 0 recs
Re: 269 equals President Biden??

Kos would explode lol.

by dtaylor2 2008-09-11 04:19PM | 0 recs
Re: Eight Key States, By The Numbers

What happens if there is an electoral tie?

Has that ever happened?

by nikkid 2008-09-11 03:50PM | 0 recs
Re: Eight Key States, By The Numbers

The analysis is too arbitrary.

Florida is out of play.  If Obama wins Florida, he won't need it; it would be a landslide.  If we're focusing on 8 states, Pennsylvania should supplant Florida.  

Then,

McCain: Ohio, Virginia, Nevada
Obama: New Mexico, Pennsylvania (this is being generous), Michigan (ditto)

with Colorado and New Hampshire being the biggest (?)'s.  

If the GOP hammers home the "Obama actively worked overtime to not count your vote" theme in Michigan or "Obama's real thoughts on Pennsylvania: cling..." theme, things can and will get ugly.  

If there's any Bradley effect in the polls, even as small as 1.5%, then this election is over before it began.  

by BPK80 2008-09-11 06:40PM | 0 recs

Diaries

Advertise Blogads