A Reminder About Probability

In just four days the USA will have a Presidential Election like it does every four years.  this year’s election cycle has been pretty heated and close.  A lot of people have a lot of opinions about the direction our nation is going, what is needed in our future President, and just the state of national politics overall.  For better of worse (which is totally a personal opinion in these matters) we’ll have chosen an individual to serve as our President for the next four next Tuesday.

In the meantime (and for like most of this year) a lot of us, who pay even a remote amount of attention to the news cycles, will keep being bombarded by polling data about the odds for which of the two major party candidates will likely win the vote.  Of course, as there often is, there is a lot of misunderstanding about all this polling data and what it means.  With that in mind I’d like to remind people something about probability.

Simply this: Probability does not equal certainty.

So, that being said, when we look at a poll analysts model, like Nate Silver’s FiveThirtyEight, and see that, as of this morning, Mr. Obama is enjoying an 80.9% probability of re-election on Tuesday, that does not mean that Mr. Obama has this election in the bag.  Furthermore, it also doesn’t mean that Mr. Romney could not win on Tuesday.  All it means, is that Mr. Obama, according to Mr. Silver’s model, is enjoy a higher probability of being elected than Mr. Romney is.

While, if you happen to be an Obama supporter and trust Mr. Silver’s math, this probability is reason to feel encouraged, it is not a reason to feel victorious.  In probability, you only ever have something in the bag, when you’ve gotten that full 100%.  Even with something like 99.9999999 . . .% there is still a probability, albeit a decreasing smaller one, that something different will occur than the favored outcome.

Both candidates, as well as media outlets, know this.  that is why  neither Mr. Romney or Mr. Obama will call it quits until all the votes are cast and the ballots counted (it’s possible they may not call it quits then either, depending on how close the numbers end up being).  While some Republicans may be feeling trepidation in these last couple days of the election it is no reason for them to concede defeat yet.  Likewise, Dems should be reserved in holding off for full celebration until they see the actual results on Wednesday morning.

So all that being said, if you see poll numbers and statistics these next couple of days, remember, that ultimately, they are only expressing probabilities.  Nothing is a certainty until all the ballots are cast and counted.

That all being said, I strongly encourage you to go vote on Tuesday, assuming that you are of legal status to do so.  Don’t let yourself be fooled by the cynicism that voting doesn’t matter.  It does, because it is a right that, throughout history, many many people, including fellow American citizens, have not always been guaranteed.

Man, won’t y’all be happy when this election season is done?  I know I will be.

~ by Nathaniel on November 2, 2012.

One Response to “A Reminder About Probability”

  1. I’ll be happy it’s done too. All that signage spoils the natural view. It was interesting to experience a lightening of my own mood about it all once I voted by mail 10 days ago. Half the people in my county have already voted! We ALL wanted it over with.

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