Show this to your friends who think 75 percent odds are practically a sure thing

[mahatmakanejeeves]

Show this to your friends who think 75 percent odds are practically a sure thing

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Politics • Analysis

Let’s talk about the odds of something happening

By Philip Bump
October 11
Several times a day, I receive a response to something I’ve written that goes something like this:

You and your polls! You said Hillary Clinton had a 90 percent chance of winning/that Clinton would win in a landslide! Polls are wrong and you don’t know what you’re talking about!

Usually those comments include other phrases meant to denigrate me on a more personal level.

It’s not the case that polling was generally wrong in 2016. Clinton had a wide advantage in the polls multiple times over the course of the campaign, but those leads consistently narrowed again. To President Trump’s benefit, one of those narrow points coincided with the Nov. 8 election. Clinton still won the popular vote by a few points -- which is what national polling predicted -- but because polls missed Trump leads in several key states, his electoral college victory was generally unexpected.

Take the election forecast at FiveThirtyEight. The site distinguished itself in 2012 by accurately predicting Barack Obama’s reelection. Coming into Election Day in 2016, it had Clinton with 71 percent odds of winning the White House. Trump had a better than 1-in-4 chance of winning, and did.

This forecast wasn’t simply a reflection of national polling and it wasn’t simply a function of state polling. It was an estimate based on running thousands of simulations of the election, resulting in a number of possible outcomes in each state. Clinton won the presidency in 71 percent of those cases. Have you seen the “Black Mirror” episode “Hang the DJ” where the two people are dating in a weird, walled-off universe? What FiveThirtyEight did was sort of like that.
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Statistical odds are one of many numerical blind spots that humans have. (Another is the vast expanse between the number “one million” and the number “one trillion.”) We see pretty good odds as suggesting that something is more of a certainty than it actually is. ... It was never the case that Clinton was a sure thing. There was always a chance that she would lose -- obviously. But that line got blurry and led to the common, incorrect line of thinking at the top of this post. ... And there is a 92 percent chance that this article won’t disabuse many stalwart adherents of that line of thinking.
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Philip Bump is a correspondent for The Washington Post based in New York. Before joining The Post in 2014, he led politics coverage for the Atlantic Wire. Follow https://twitter.com/pbump

[MarvinGardens]

1. Many don't understand measurement uncertainty either.

And upon realizing that a scientific measurement or prediction will have some uncertainty, those same folks shrug their shoulders and say it's all bunk. Either it must be 100% accurate all the time, or else it must be a scam.