Presidential Prediction Contest

Modesty forbids me, but honesty compels me: my 15-month-old predictions for the 2008 Presidential elections have thus far been so spot-on, it’s spooky. I know that many of you have clamored for us to drop the science stuff from our blog entirely, and just talk about politics and/or our personal lives, topics that are severely under-served in the blogosphere. My own preference would be to focus exclusively on physics, to the exclusion of any other topic of any possible interest, but who am I, anyway? This is a blog, after all, and I think we can all agree that the loudest commenters should have final say on what we post about.

Therefore, I feel compelled to offer up another round of predictions, now that we’ve narrowed the field to two major candidates. By why not make it more fun and have a prediction contest? Anyone can join in, just by leaving your prediction the comments. Entries that appear before the end of June will officially count.

But to make things somewhat science-y, let’s use equations to judge who will win. Each prediction consists of two numbers: the fraction f of the total popular vote cast for the two major candidates that goes to Barack Obama, but also the standard deviation σ of your prediction for that percentage. We are thus ignoring the electoral college entirely, and dealing with the annoyance of third-party candidates by concentrating exclusively on McCain vs. Obama. And we are assuming for purposes of misleadingly-precise quantification that each prediction follows a normal (Gaussian) distribution:

$latex displaystyle P(x) = frac{1}{sigma sqrt{2pi}} expleft(-frac{(x-f)^2}{2sigma^2}right) ,.$

And here is the rub: the winner is not the one whose fraction f is closest to the final answer, but the one whose value of P(x) is the highest, when x is equal to the fraction of votes Obama actually does win. The smaller your standard deviation is, the higher your P(x) will be for x very close to your predicted value f , but the faster it will die off as you get further away. So if you are extremely confident, you can ensure victory by choosing an appropriately tiny standard deviation on your prediction. Contrariwise, if you choose a large standard deviation, you might get lucky if none of the confident folks comes close to the actual result. Cool, eh?

So here we go: I predict that Obama will win 55.5% of the popular vote fraction, with 1.5% standard deviation. That’s right — a blowout. Might be crazily optimistic of me, but right now the portents are good. In Obama’s favor, the current electoral map is extremely favorable (not that it matters for our contest), he is an energetic and charismatic campaigner, his organization is impressively seasoned and effective, he will have twice as much money to spend, Democratic identification among voters is soaring, the incumbent President is world-historically unpopular, various economic crises are putting the squeeze on middle-class voters, the war in Iraq is hugely unpopular, and McCain is a bumbling and unconvincing candidate with a tattered organization, little support among the party faithful, a disturbing penchant for changing his mind and misunderstanding his own policies, and little interest in anything other than foreign policy. In McCain’s favor, Obama is black and his middle name is Hussein; also, McCain has a great rapport with the press, who respect his maverick image. Overall, I think the scales are pretty heavily tilted on this one, and I will not be surprised if McCain replaces Bob Dole as the Presidential candidate that Republicans would most like to pretend never happened.

Of course, I could be wrong. So let’s hear your predictions! The winner will receive a lifetime subscription to Cosmic Variance. Or maybe a T-shirt, if we get caught in a generous mood.

114 Comments

114 thoughts on “Presidential Prediction Contest”

  1. Duh. I reread the blog post and realized that f is Obama’s percentage regardless of whether he wins. So please change my prediction to f=45, sigma=1.2

  2. I know a guy who always bets against his favorite sports team, because he figures that way he’s either happy that his favorite team won, or happy that he made some money. Going along similar reasoning, and taking into account that the 100+ posts above me have already covered most reasonable predictions, I’ll instead predict:

    f = 30%, sigma = 5%.

  3. There will be a Terrorist Attack on a debate between Obama and McCain and Bush will declare Marshall Law to become Dictator.Will Americans react with fear or anger?

  4. There are rumors going around about the existence of a secret society called “The Black Door” that was formed explicitly to ensure that George Bush leaves office in November when he is supposed to.

  5. Sean,

    What do you mean by “In McCain’s favor, Obama is black and his middle name is Hussein” ?

    If you imply that these are the only reasons people won’t vote for Obama, this is simply intellectually dishonest (a charge I would have never thought I could accuse you of).

    There are plenty of reasons not to be taken by the Obama-mania that has engulfed so many educated and smart people: Wright and Obama’s association with a racist church for 20 years (20!!!), Obama’s willingness to meet with Ahmadinejad without condition (afterwards retracted), Obama’s impulse to say things in front of whatever audience to please it and then retracting (“clarifying”) what he said (like his position on NAFTA, his speech to AIPAC, ….), Obama’s association with less than savory deal makers (real estate profit on his property in Chicago and such), and so on and so forth.

    All this leaves either one to doubt the “change” in Obama’s program and the value of his character or just reinforce the idea that he is an unknown and untested senator (he basically ran for President as soon as he got to the Senate…).

    The more I learn about him, the more he appears as a “standard” politician, with very unsavory friends and associations who don’t seem to trouble him that much as long as he gets what he wants (money, political clout, …).

    I won’t vote for him come November and it has nothing to do with the color of his skin or his middle name.

    Hillary would have been a better choice for the Democrats but as the saying goes “they never miss an opportunity to miss an opportunity”…

  6. let me just make a quick note (as a public service/reality check) of what we think the chances are that Obama will win the popular vote are (Included are all valid predictions, according to the rules laid out by Sean, whose prediction I cite as “number 0”).
    my own guess is f=50.1, sigma=1 (in percent. i’m more concerned with being right than winning…)

    0:100
    2 : 84.1
    3 : 2.2
    4 : 2.2
    6 : 100
    7 : 100
    8 : 100
    9 : 100
    10 : 100
    12 : 100
    14 : 12
    18 : 77.3
    19 : 88.5
    20 : 98.6
    23 : 100
    25 : 100
    29 : 73.4
    30 : 100
    31 : 6.7
    32 : 4.8
    34 : 0
    35 : 100
    37 : 99.4
    38 : 98.6
    39 : 100
    40 : 100
    41 : 100
    42 : 2.2
    45 : 100
    47 : 99.9
    49 : 100
    50 : 100
    52 : 0
    53 : 100
    55 : 100
    56 : 100
    57 : 79.8
    58 : 100
    59 : 100
    61 : 100
    62 : 100
    63 : 100
    64 : 100
    66 : 99.8
    67 : 100
    68 : 100
    71 : 0
    72 : 0
    73 : 97.7
    75 : 94.9
    76 : 100
    77 : 94.7
    80 : 100
    81 : 2.3
    82 : 100
    86 : 91.9
    90 : 100
    91 : 100
    92 : 100
    93 : 99.0
    95 : 97.7
    97 : 100
    98 : 0
    100 : 100
    102 : 0
    103 : 0
    107: 54.9 (self)

  7. Way more fun would be to have every prediction be obama %, senate dem # (sanders yes, lieberman no), house dem #. The winner would be the one with the highest product of the three probabilities. This reduces the silly incentive to be overprecise with your sigma. You could even decline to guess in a category and get the average probability from all stated guesses. (Would DTG, DTG, DTG be a winning strategy? Probably not – but as # of categories grew, and thus incentive for overprecision went to zero, it could definitely become one!)

    So: Obama 56.6, stdev .5 is my prediction for the contest as stands (and I’d do the sha hash thing – I actually have a python interpreter with the module loaded in another window! – but I’m too lazy to save my answer separately). But for my rules, I would take O 54 sigma 3, D 56.5 sigma 1.2, D 250 sigma 10 (lazy).

  8. Ilana on Jun 30th, 2008 at 10:49 pm:


    Sean,

    What do you mean by “In McCain’s favor, Obama is black and his middle name is Hussein” ?

    If you imply that these are the only reasons people won’t vote for Obama, this is simply intellectually dishonest (a charge I would have never thought I could accuse you of).

    ~~~~~~~~~~~~~~~~~~~~~~~

    Saying that something about an opponent is in a candidate’s favor only means that an appreciable sector of voters will be turned off by it. There isn’t any reason to suppose that would be “the only reason” they wouldn’t vote for that candidate. I don’t get why so many people have trouble with multiple causation issues.

    BTW, McCain has recently admitted he is computer illiterate and relies on his wife for those things. That isn’t good for the leader of an advanced nation in the information age.

  9. Pingback: Prediction Contest Update | Cosmic Variance

  10. Who won? I said Obama gets 52.5% of vote with 1% st.dev. CNN says Obama won 53.2%. This gives me a P = 31.2.

  11. Pingback: Prediction Contest Results! | Cosmic Variance | Discover Magazine

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