Obama—Romney 2012

ObamaRomney
98.9% probability of winning 1.1% probability of winning
Mean of 311 electoral votesMean of 227 electoral votes

Electoral College Map

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Electoral College Map

GeorgiaAlaskaArizonaArkansasCaliforniaColoradoDelawareConnecticutFloridaMississippiAlabamaHawaiiIdahoIllinoisIndianaIowaKansasKentuckyLouisianaMaineMarylandMassachusettsMichiganMinnesotaMissouriMontanaNebraskaNevadaNew HampshireNew JerseyNew MexicoNew YorkNorth CarolinaNorth DakotaOhioOklahomaOregonPennsylvaniaRhode IslandSouth CarolinaSouth DakotaTennesseeTexasUtahVermontVirginiaD.C.WashingtonWest VirginiaWisconsinWyoming

Huh. Four years ago at this time, I was frantically entering the eleven new polls that had come out on election day. Today…not so much. We get only one rather inconsequential poll, although because it is Maine, and the Congressional districts are reported, we get three new polls for the price of one.

startendsample%%%
stpolldatedatesizeMOEORdiff
MEMaine PRC01-Nov03-Nov9053.353.342.2O+11.1
ME1Maine PRC01-Nov03-Nov46956.739.0O+17.7
ME2Maine PRC01-Nov03-Nov43649.745.7O+4.0

As a consequence, this analysis differs little from yesterday’s analysis.

After 100,000 simulated elections, Obama wins 98,946 times and Romney wins 1,054 times (including the 180 ties). Obama received (on average) 311 (+2) to Romney’s 227 (-2) electoral votes. In an election held now, Obama would have a 98.9% (+0.1%) probability of winning and Romney would have a 1.1% (-0.1%) probability of winning.

My prediction: Obama wins. It’s almost certain.

Here’s our look back over the race from a series of elections simulated every seven days using polls from 06 Nov 2011 to 06 Nov 2012, and including polls from the preceding seven days (FAQ).

The interesting thing is the very ragged, multimodal distribution of electoral votes seen in the graph below. The single most likely outcome in this race is an Obama victory with 303 electoral votes. There is a 9.2% probability of that happening.

Then it jumps to 332 electoral votes, with a 6% probability. And then to 318 electoral votes with a 3.8% probability. And so on.

The raggedness of the electoral votes distribution reflects that there are a non-trivial number of important states with large uncertainty. Florida is Romney’s but with only a 63% probability. Iowa is Obama’s but with only an 84% probability. North Carolina is in Romney’s column, but with a 74% probability, and Virginia goes to Obama, but with a 78% probability.

Ten most probable electoral vote outcomes for Obama (full distribution here):

  • 303 electoral votes with a 9.19% probability
  • 332 electoral votes with a 5.94% probability
  • 318 electoral votes with a 3.80% probability
  • 304 electoral votes with a 3.78% probability
  • 290 electoral votes with a 3.49% probability
  • 319 electoral votes with a 3.30% probability
  • 297 electoral votes with a 2.97% probability
  • 314 electoral votes with a 2.30% probability
  • 312 electoral votes with a 2.23% probability
  • 333 electoral votes with a 2.11% probability

After 100,000 simulations:

  • Obama wins 98.9%, Romney wins 1.1%.
  • Average (SE) EC votes for Obama: 310.7 (19.3)
  • Average (SE) EC votes for Romney: 227.3 (19.3)
  • Median (95% CI) EC votes for Obama: 308 (276, 347)
  • Median (95% CI) EC votes for Romney: 230 (191, 262)

Each column of this table shows the electoral vote total aggregated by different criteria for the probability of winning a state (Safe=100%, Strong=90%+, Leans=60%+, Weak=50%+):

ThresholdSafe+ Strong+ Leans+ Weak
Safe Obama159
Strong Obama124283
Leans Obama2020303
Weak Obama000303
Weak Romney000235
Leans Romney4646235
Strong Romney129189
Safe Romney60

This table summarizes results by state. Click on the poll count to see the individual polls included for the state.

00EC#Total%%ObamaRomney
84VotespollsVotesObamaRomney% wins% wins
AL91*404 39.6 60.4 0.2 99.8
AK30*(0)(100)
AZ1111069 46.5 53.5 5.1 94.9
AR61*571 34.9 65.1 0.0100.0
CA553*2986 57.3 42.7100.0 0.0
CO954007 52.1 47.9 97.3 2.7
CT711183 56.7 43.3 99.9 0.1
DE30(100)(0)
DC31*1173 91.6 8.4100.0 0.0
FL2987066 49.7 50.3 37.3 62.7
GA1611276 46.4 53.6 3.1 96.9
HI41*1157 64.2 35.8100.0 0.0
ID41*563 30.0 70.0 0.0100.0
IL2011174 58.2 41.8100.0 0.0
IN111570 45.3 54.7 5.7 94.3
IA675348 51.0 49.0 84.4 15.6
KS62*1143 39.4 60.6 0.0100.0
KY81*557 42.4 57.6 0.6 99.4
LA81*2548 37.9 62.1 0.0100.0
ME233005 55.9 44.1100.0 0.0
ME1121250 59.8 40.2100.0 0.0
ME2131700 52.2 47.8 89.7 10.3
MD102*1538 61.6 38.4100.0 0.0
MA1132556 58.2 41.8100.0 0.0
MI1654920 51.7 48.3 95.8 4.2
MN1031953 54.4 45.6 99.8 0.2
MS62*1420 43.2 56.8 0.0100.0
MO1032536 45.1 54.9 0.0100.0
MT321411 45.7 54.3 1.2 98.8
NE211119 43.2 56.8 0.0100.0
NE111*389 45.5 54.5 11.1 88.9
NE211*646 47.4 52.6 17.4 82.6
NE311*284 35.9 64.1 0.0100.0
NV621298 52.5 47.5 90.6 9.4
NH486212 51.2 48.8 91.9 8.1
NJ145*3773 55.6 44.4100.0 0.0
NM52*1307 54.8 45.2 99.0 1.0
NY293*1770 63.8 36.2100.0 0.0
NC1532709 49.2 50.8 26.3 73.7
ND34*2563 42.6 57.4 0.0100.0
OH1898649 51.5 48.5 97.9 2.1
OK71*279 35.8 64.2 0.1 99.9
OR71903 53.0 47.0 90.6 9.4
PA2053892 51.6 48.4 91.9 8.1
RI41*523 62.1 37.9100.0 0.0
SC93*4199 48.2 51.8 4.1 95.9
SD31595 43.7 56.3 1.4 98.6
TN111*566 36.6 63.4 0.0100.0
TX381*752 41.5 58.5 0.1 99.9
UT61594 26.3 73.7 0.0100.0
VT31*415 71.3 28.7100.0 0.0
VA1365538 50.7 49.3 77.5 22.5
WA121923 53.5 46.5 93.5 6.5
WV51*361 42.1 57.9 1.7 98.3
WI1022409 52.5 47.5 95.7 4.3
WY30(0)(100)

* An older poll was used (i.e. no recent polls exist).

Details of the methods are given in the FAQ.