|99.9% probability of winning||0.1% probability of winning|
|Mean of 327 electoral votes||Mean of 211 electoral votes|
Last week’s analysis showed President Barack Obama leading Romney with an average of 323 to 215 electoral votes in a hypothetical election held then. The results suggested Obama had a 99.3% to Romney’s 0.7% probability of winning.
Since then, eleven new polls have been released (although only a couple of the polls were administered after last Thursday’s Supreme Court ruling on the Patient Protection and Affordable Care Act):
|AL||Capital Survey Research Center||06-Jul||06-Sep||841||3.3||33.9||55.8||R+21.9|
Alabama is solid for Romney (+21.9%), as Massachusetts is for Obama (+16%). Arizona is turning into a solid Romney state. He has led in the past five polls, going back to mid-April.
Obama solidifies the three “classic swing states.” In Florida, Obama leads in both polls by +0.8% and +4%. Combined with the one other recent poll, Obama would be expected to take the state now with a 93% probability.
In Ohio, Obama has a +9% in the new poll, giving him the lead in both current OH polls; he would be expected to win the state now with a 99% probability. Romney seemed to made some headway in late May and early June, but that “surge” now seems transient:
The Ohio story is repeated for Pennsylvania where Obama has a modest +6% lead over Romney, leads in both current polls, and would win with a 99% probability. The difference is a lack of evidence for a transient Romeny surge for the state:
North Carolina is interesting. Romney goes up +5% in one poll and Obama goes up by +2% in the other new poll. Romney now leads in three of the four current polls, and would be expected to take the state with a 71% probability:
Michigan has Obama up by a moderate +5% over Romney. The state has gone from a tie one year ago, to a solid Obama lead since January, back down to a small advantage for Obama in the past few weeks:
Finally, the new New Hampshire poll gives Obama a not-so-impressive +1% lead over Romney. Still, the larger trend and the recent flurry of polls has the state painted blue:
With these new polls (and some older ones dropping out), the Monte Carlo analysis gives Obama wins 99,860 times and Romney wins 140 times (including the 41 ties). Obama receives (on average) 327 (+4) to Romney’s 211 (-4) electoral votes. In an election held now, Obama would win with a 99.9% probability.
Here is the distribution of electoral votes [FAQ] from the simulations:
Ten most probable electoral vote outcomes for Obama:
- 328 electoral votes with a 4.52% probability
- 322 electoral votes with a 4.40% probability
- 323 electoral votes with a 3.94% probability
- 329 electoral votes with a 3.76% probability
- 334 electoral votes with a 2.63% probability
- 313 electoral votes with a 2.60% probability
- 333 electoral votes with a 2.56% probability
- 325 electoral votes with a 2.45% probability
- 319 electoral votes with a 2.44% probability
- 337 electoral votes with a 2.40% probability
After 100,000 simulations:
- Obama wins 99.9%, Romney wins 0.1%.
- Average (SE) EC votes for Obama: 326.6 (15.9)
- Average (SE) EC votes for Romney: 211.4 (15.9)
- Median (95% CI) EC votes for Obama: 328 (293, 357)
- Median (95% CI) EC votes for Romney: 210 (181, 245)
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%+):
|Threshold||Safe||+ Strong||+ Leans||+ Weak|
This table summarizes results by state. Click on the poll count to see the individual polls included for the state.
|8||4||Votes||polls||Votes||Obama||Romney||% wins||% wins|
* An older poll was used (i.e. no recent polls exist).
Details of the methods are given in the FAQ.
The most recent analysis in this match-up can be found from this page.