This might be my favorite graph that we've done so far: a comparison of Barack Obama's popular and electoral vote totals across the first 1,000 simulations that we ran last night:
Several interesting things to point out:
1. The relationship between the popular vote and the electoral vote is approximately linear, except at the endpoints. As a rule of thumb, a gain of one percentage point in a Obama's popular vote share results in a gain of 25 electoral votes. This is also, you will note, a pretty steep slope. If Obama wins the election by 4 percentage points, he projects to win by approximately 100 electoral votes (319-219).
2. The regression line crosses the y-intercept at 269.3 electoral votes, which is almost exactly half of 538. That means that there does not appear to be any systematic advantage in the electoral vote math to one candidate or another, at least based on our present rendering of these numbers.
3. Where you do see a little bit of skew are those scenarios where one candidate wins by about 5-15 percentage points. In those cases, the winning candidate tends to win by more electoral votes than is predicted by the regression line. This is because an especially high number of states are within reach for one or another candidate. In contrast to 2004, when 16 states and the District of Columbia were decided by 20 or more points, very few are polling that way this year.
4. The range of possible outcomes given any specific value of the popular vote is about 80-100 electoral votes wide. For example, an Obama win by 5 percentage points could easily be associated with any number from about 290 electoral votes up to as many as 390, depending on how the individual states shake out. Likewise, for any given value of the electoral vote, the range of the popular vote margin is about 6 or 7 percentage points wide. What this means, among other things, is that it's virtually impossible for a candidate to win the electoral college while losing the popular vote by more than about 3 or 3.5 percentage points.
Monday, June 16, 2008
Popular Vote v Electoral Vote
-- Nate Silver at 3:24 PM
Labels: electoral math, meta, popular vote
52 comments
Nice, so Obama stands to be very far ahead if current environment holds, I look forward to the landslide (26.13% chance)
Lets see if Rasmussen gives Obama a bounce in Virginia in their poll to be released at 5
Wait a minute, I don't think I agree with point 3. If the data points are below the regression line when McCain wins by 5-15%, then Obama is getting FEWER electoral votes relative to the popular vote support he is getting than at other points in the graph. This is the opposite of what is stated in point 3.
Oops, I think you're right @3:51. Let me fix.
And the VA poll is out! (Rasmussen)
Obama 45 (44)
McCain 44 (47)
(May 8th results in parenthesis.)
This is all syncing up nicely now. RCP has the national poll average around Obama+3.5 right now, which your graph maps to about 300 EVs, right where your state-by-state projection is holding. Nice job!
On the subject of Rasmussen, I've been following their Bush Approval ratings for years. They swear by their "strongly versus somewhat" methodology, which results in a nominally higher "approval" rating for Bush.
Nevertheless, it's down to 31%, but the figure I keep watching is "strongly disapprove". If that ever breaks 50% I'll consider it a tipping point, because I don't trust the "somewhat disapprove" gang to vote against McCain. This week, "strongly disapprove" reached a new record high: 49%.
Almost there!
New Ras Poll out for VA:
http://www.rasmussenreports.com/public_content/politics/election_20082/2008_presidential_election/virginia/election_2008_virginia_presidential_election
Obama 45% McCain 44%
VOTE MCCAIN!! OBAMA IS A MUSLIM!!!
Oy, well blogs are all about user interaction, but do you police trolls at all, Nate? Unless that's a rather inane stab at irony.
Anyways, Mr. Anonymous,
http://www.isbarackobamaamuslim.com
VOTE OBAMA!! MCCAIN IS A QUAKER!!!!
Err, but anyway. Interesting to see that the Electoral College seems like it really does mostly mirror the popular vote, at least on average. I can't decide whether to view the accuracy of the approximation as better than I feared or worse than I hoped, though.
Anonymous said...
VOTE MCCAIN!! OBAMA IS A MUSLIM!!!
---
thats the best you can do ?
lol
another brain dead human
VA is really looking good for OBAMA
The best news for Obama in the latest Virginia poll is that almost all the movement has come from Independents, Obama has seen only an increase of 1 % among democrats from 75 to 76 which shows amazing growth potential he has in this state. He is 1 point ahead of McCain despite only getting 76 % of democrats! And the number of dems supporting Obama is only going to go up.
On a side note it looks like the new version was bang on... this poll supports the results of v2 of this site with Virginia moving from a slightly pink to pure toss-up. Here's hoping we get some new polls from Ohio and Pennsylvania soon.
Anonymous said...
More good news for McCain!!!!
http://tour.rustytrombone.com/aa/index.php
----
don't go to the site
its porn
admin
remove the post
One thing that's interesting about the new methodology is that in theory it ought to diminish the effect of any given new poll because an attempt has already been made, implicitly, to "guess" what that poll might say. Today's VA poll, for example, would likely have had more impact on the old model; now all it's doing is providing data to back up what the model is already guessing in the absence of data.
I miss the win percentage versus time graph, though. I think especially with the new methodology that would be a very useful way to get an impression of when something happened that really did represent a change in the race.
And did anyone mention "bring back the cartogram!" in this thread yet?
Nate:
Does Missouri really belong in the "Highlands" (read: Appalachia) category along with TN, KY, AR, WV, and OK? Missouri doesn't seem to be demographically similar to those other states. I would think it would belong in the "North Central" along with Illinois and Iowa.
re: Stephen
Hey!! I'm a Quaker, and I'm offended by your implication that McCain is one of us! I'll have you know, we Quakers have a celebrated history in the Oval Office: uh, well, erm, Hoover and, sorta, Nixon.
Dammit, nevermind. :-)
I am a fan of this site and I am still getting used to the changes that were made a couple of days ago. I've read and reread the explanation of the changes and I think I understand it as well as some of the comments -- some of the deeper ones are beyond me. Sort of makes me feel bad for blowing off some of those stats classes when I got my poly sci degree 25 years ago...
Question, given your ability to profile each state and every CD, perhaps your map could have a special pop-up section for those two congressional districts in Nebraska that Obama may be competitive in and we could see if this current "rising tide" of national poll support is project to flip one or two of those districts?
Stuart:
Because the revamp shifted the win % so dramatically it's difficult to see how to put it back up there without looking weird (and without going all the way back and rerunning future-projections in the past, which seems a bit unnecessary). Plus, the super-tracker seems to track what I remember from the win% tracker pretty well.
Oh yeah. Bring back the cartogram!
I just found this blog and it's interesting. Perhaps the anonymous commenting feature could be disabled though...
This is because an especially high number of states are within reach for one or another candidate. In contrast to 2004, when 16 states and the District of Columbia were decided by 20 or more points, very few are polling that way this year.
This is an interesting point in and of itself. Could the fact that there are very few blowouts, as of right now, be actually a predicator of how much the numbers will eventually move: vis a vi, you now use months away from election as a factor in predicting how much the ultimate results will possibly move. Would it be better to use amount of blowouts instead of time as a gage for how likely the numbers are to move as we approach election day?
I have to imagine that there are going to be more blowouts, for both the Republicans and Democrats, as we move closer towards election day?