It’s been a long time since I done these analyses—just over a month. I quit doing them after Mitt Romney became the presumptive nominee. I pointed out that:
The effective end of the Republican primary this week should mark a change in the dynamics of this race. Expect Romney’s chances to improve considerably as new polls roll in. The full effect may not be seen for another month (depending on the frequency and diversity of polling).
Since Pres. Obama was beating Romney in 100% of the simulated elections, with an average electoral vote total of 347 to 191, it seemed silly to keep doing these analyses until the race looked a bit more “post-primary.”
Since that last analysis, 50 new polls have come out, covering 26 different states. (Still no new S.C. poll…sorry.) I guess it’s time to see how Obama and Romney stack up.
First, I should mention that the National polls make the race appear to be very close. The Real Clear Politics average of national polls has Obama leading Romney by +1.7%. The problem is, the national polls reflect the national vote. And as we remember all too well from 2000, the national vote does not always go the way of the Electoral College.
That is why I do these analyses. I collect only the state head-to-head polls and use them to infer the winner of the Electoral College. So, with an (apparently) close popular vote, how does the election look?
After 100,000 simulated elections, Obama wins 99,890 times and Romney wins 110 times (and we even give him the 12 ties). Obama receives (on average) 333 to Romney’s 205 electoral votes. In an election held now, Obama would be expected to win with a 99.9% probability to Romney’s 0.1% probability.
Huh…the “post-primary” election has hardly changed.
|99.9% probability of winning||0.1% probability of winning|
|Mean of 333 electoral votes||Mean of 205 electoral votes|
Here is the distribution of electoral votes [FAQ] from the simulations:
Ten most probable electoral vote outcomes for Obama:
- 328 electoral votes with a 2.65% probability
- 319 electoral votes with a 2.49% probability
- 318 electoral votes with a 2.37% probability
- 327 electoral votes with a 2.35% probability
- 338 electoral votes with a 2.25% probability
- 329 electoral votes with a 2.15% probability
- 312 electoral votes with a 2.08% probability
- 348 electoral votes with a 1.95% probability
- 313 electoral votes with a 1.93% probability
- 347 electoral votes with a 1.75% probability
After 100,000 simulations:
- Obama wins 99.9%, Romney wins 0.1%.
- Average (SE) EC votes for Obama: 332.7 (23.4)
- Average (SE) EC votes for Romney: 205.3 (23.4)
- Median (95% CI) EC votes for Obama: 331 (291, 382)
- Median (95% CI) EC votes for Romney: 207 (156, 247)
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.