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Probabilities of Electability #3

Votemaster Andrew Tanenbaum has several new general election polls available at <a href="http://www.electoral-vote.com">electoral-vote.com</a>, so I reran Monte Carlo simulations of the general election using both the Obama/McCain and Clinton/McCain polling data.

As before, I've run 10,000 trials for each, assuming a 4% margin of error in each state poll, and that the sampling error in each state is an independent random variable.

This week's polls bode well for both Democratic candidates. Tanenbaum's site allocates the electoral votes by who is ahead in a given state, and now gives Obama a <a href="http://www.electoral-vote.com/evp2008/Obama/Maps/May02.html">264-263</a> electoral vote lead over McCain. Hillary has a more solid lead, <a href="http://www.electoral-vote.com/evp2008/Clinton/Maps/May02.html">291-236</a>.

My simulation results:
Obama wins 79.4%, average 292.9 EV
McCain wins 17.5%, average 245.1 EV
Electoral tie 3.1%

Clinton wins 97.1%, average 289.1 EV
McCain wins 2.43%, average 248.9 EV
Electoral tie 0.47%

Now both Democrats would quite likely win against McCain, and Clinton would win almost all the time. Interestingly, Obama has a slight edge in average electoral votes, becuase McCain's slim 1 point leads in Ohio, Florida, and Texas mean that Obama wins at least one of these big states most of the time.

Clinton has slight leads in several states, but in the current map basically all the close states would have to break against her for McCain to beat her, which is why she wins over 97% of the simulated elections.

Compared to my <a href="http://tpmcafe.talkingpointsmemo.com/talk/2008/04/the-probabilities-of-electabil.php">two</a> <a href="http://tpmcafe.talkingpointsmemo.com/talk/2008/04/probabilities-of-electability.php">previous</a> simulations, Obama has his biggest lead over McCain, as he's put Florida and Ohio very much in play, and he's swung Pennsylvania much more solidly into his column. Both Democrats have their best showings against McCain now, by far.

Clinton has a 10 point lead in Ohio, 9 in Pennsylvania, and 8 in Florida, taking all the key swing states from the 2004 election. If she can hold these leads for the fall, that would virtually guarantee she would win.

Former British Prime Minister Harold Wilson famously said, "A week is a long time in politics", and my simulations indeed reflect that. In just a week, both Democratic candidates have shifted from being virtually tied with McCain to being quite likely to beat him. This is circumstantial evidence that the continued nomination struggle isn't as damaging as many pundits think.

My opinion is still that Obama would likely run stronger in the fall, or at least that he's much more likely to win in a landslide. But based on the current polling numbers, while both Democratic candidates are currently strong against McCain, Clinton appears the stronger of the two.





Comments (5)

Your post is incomprehensible. What do you mean by 79% and 97%?

Actually, I do understand what you are saying.
It just happens to be nonsense.
You cannot project current state-by-state polling preferences half a year into the future with any claim of mathematical reliability.

I suppose I should clarify further: this is not a prediction of what I expect to happen 6 months from now; it's a simulation based on what the polling data currently show.

At best, the polls are a snapshot of public opinion from the time they are taken, and I agree with you that much can, and will, change between now and then. The value of the simulation is that, unlike simply summing electoral votes for who is leading in each state, and seeing who the winner is, this simulation allows cases where you may lose states you're currently winning, and vice-versa. And the likelihood of winning or losing a state is proportional to how large your lead (or deficit) is in that state.

People already look at national head-to-head polling numbers, which are interesting, but beside the point, because of the electoral vote process used to determine the winner. The Votemaster's site uses state-by-state polling, which is a better snapshot of who is currently ahead. I think my simulation improves the picture a little more, because it allows for variation in state-by-state outcomes.

The probabilities will change as new polling data is released, and I plan to continue to track and report the results. I feel it's certainly no worse than looking at state-by-state polls, which lots of people do find interesting.

I don't agree with you, but I like your dog. ;)

Thanks!

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