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2016 Postmortem
Related: About this forumSam Wang of Princenton EC explains how polls are valued and used Very interesting & COMFORTING
for those worried and wondering how accurate the polls/predictions are.
Presidential prediction 2012 (Election Eve)
November 6th, 2012, 1:47am by Sam Wang
If state polls perform as well as they did in 2004 and 2008, most aggregators should get within +/-15 electoral votes and 48/51 races correct. The question is how to squeeze a bit more out of the data.
The topline listed just below the title of this website is not our prediction, but the automatically-generated snapshot. It will fluctuate as the last few polls trickle in. The last 3 updates are at 8:00am, 10:00am, and noon. Then we freeze it.
I make two electoral predictions.
ELECTORAL PREDICTION (mode): Barack Obama 332 EV, Mitt Romney 206 EV. The mode is the single most frequent value on the histogram. It corresponds to the map below, and has a chance of being exactly correct.
ELECTORAL PREDICTION (median): Obama 309 EV, Romney 229 EV, Popular Vote Meta-Margin Obama +2.34%. This is the automatically-generated snapshot for November 5th 8:00pm. This prediction is almost guaranteed to be off, since 309 EV is not a common combination. (Note: Ill edit this with the last few updates.)
ALL-STATE PREDICTION (binary outcomes):
Most outcomes arose clearly from the median of the last week of polling. The exception was Florida, for which I used polls with at least half of their respondents on Nov. 1 or after. This gave a median margin of Obama +0.5 +/- 0.8% (n=10), for a win probability of 72%. I will be unsurprised for it to go the other way (outcome Obama 303 EV, Romney 235 EV). In Florida, a recount is triggered by a margin of 0.5% or less (recount rules, Brennan Center for Justice). There is about a 50-50 chance that we will see that happen.
The next-closest states are Colorado, Virginia, and North Carolina, with margins of less than 2.0%. Excluding these three states and Florida still leaves Obama 281 EV, Romney 191 EV.
In addition to all-or-none outcomes, later today I will provide final polling medians in graphical form in the Geeks Guide. I hope it will be useful as you follow the returns.
November 6th, 2012, 1:47am by Sam Wang
If state polls perform as well as they did in 2004 and 2008, most aggregators should get within +/-15 electoral votes and 48/51 races correct. The question is how to squeeze a bit more out of the data.
The topline listed just below the title of this website is not our prediction, but the automatically-generated snapshot. It will fluctuate as the last few polls trickle in. The last 3 updates are at 8:00am, 10:00am, and noon. Then we freeze it.
I make two electoral predictions.
ELECTORAL PREDICTION (mode): Barack Obama 332 EV, Mitt Romney 206 EV. The mode is the single most frequent value on the histogram. It corresponds to the map below, and has a chance of being exactly correct.
ELECTORAL PREDICTION (median): Obama 309 EV, Romney 229 EV, Popular Vote Meta-Margin Obama +2.34%. This is the automatically-generated snapshot for November 5th 8:00pm. This prediction is almost guaranteed to be off, since 309 EV is not a common combination. (Note: Ill edit this with the last few updates.)
ALL-STATE PREDICTION (binary outcomes):
Most outcomes arose clearly from the median of the last week of polling. The exception was Florida, for which I used polls with at least half of their respondents on Nov. 1 or after. This gave a median margin of Obama +0.5 +/- 0.8% (n=10), for a win probability of 72%. I will be unsurprised for it to go the other way (outcome Obama 303 EV, Romney 235 EV). In Florida, a recount is triggered by a margin of 0.5% or less (recount rules, Brennan Center for Justice). There is about a 50-50 chance that we will see that happen.
The next-closest states are Colorado, Virginia, and North Carolina, with margins of less than 2.0%. Excluding these three states and Florida still leaves Obama 281 EV, Romney 191 EV.
In addition to all-or-none outcomes, later today I will provide final polling medians in graphical form in the Geeks Guide. I hope it will be useful as you follow the returns.
[img][/img]
http://election.princeton.edu/2012/11/06/presidential-final-prediction-2012-election-eve-final/
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Sam Wang of Princenton EC explains how polls are valued and used Very interesting & COMFORTING (Original Post)
courseofhistory
Nov 2012
OP
SheilaT
(23,156 posts)1. As I recall, in 2008 Nate Silver only
got one state wrong. I'm thinking it was Missouri, but not entirely sure.
Hokie
(4,288 posts)2. Silver's only miss was Indiana
He predicted McCain and Obama won by 1%.
hogwyld
(3,436 posts)3. Close. It was actually IN
That Nate missed on.
octoberlib
(14,971 posts)4. It was Indiana. They went for Obama by 1%. nt
Yavin4
(35,450 posts)5. And Missouri Was Damn Close
It took a couple of days to declare the winner there.
SheilaT
(23,156 posts)6. Aha! That's why I'm mis-remembering his one wrong call
as Missouri.
Grammy23
(5,815 posts)7. Wasn't Sam Wang's 2008 prediction off by just 1 Electoral vote?
courseofhistory
(801 posts)8. yes....n/t
onecent
(6,096 posts)9. This guy, Sam Wang was only off by 2 EV???? WOW. Where has he been
I have never heard of this before. THANK YOU FOR POSTING - whoever posted this...sorry, i was responding because I couldn't believe how accurate this fella was. I was aware of Nate Silver, but it's WONDERFUL to know about both of these. WOW