Wednesday, November 07, 2012

These US elections are more complex than I realised.

The internet is all agog with talk of Nate Silver and how he got the election right. So, I went to have a look and he seems to have called the race at 313 (Obama) / 225 (Romney). That seems very impressive to me.

However, I hate to be picky but whilst the prediction was close it doesn't seem to be actually right. It seems the result will end up 332 / 206 when Florida calls (assuming Obama wins). I've been told that actually Nate predicted a broader range and that 313 / 225 was the average - so he was hedging.

That's ok then. Still, it's very impressive and yes the twitter verse is flowing with #natesilverfacts

Now, as impressive as Nate Silver's prediction was, it seems that Drew Linzer who has predicted an Obama win since June with a 90%+ certainty and the right range, made his prediction of 332 / 206 which is also what he has been predicting since June.

Hang on - 332 / 206 - that's what seems to be happening. That's no hedge, that's just oh wow. Has Drew Linzer really nailed it? Since June?

Every state, every forecast - on the money. That's real wow. That's mega mega wow with wow sauce on.

That's more than just impressive that's so impressive that there must be ... wait ... 

Where's the #drewlinzerfacts?

Hint : There aren't any. 

Now, both Nate Silver and Drew Linzer have certainly made exceptional predictions here and despite the hedging  on the overall count on Nate's part, his overall predictions on % vote for each candidate squeaked past Drew i.e. Nate Silver was more accurate in 26 States whereas Drew was more accurate in 24 States.

But why the silence on Drew Linzer? If Florida goes the way expected then :-

#NateSilver can beat the sun in a staring contest but only Drew Linzer can make it run and hide #drewlinzerfacts

OK, this most be some sort of special US Election thing that I'm not getting seeing that I'm a Brit. I'm a huge fan of people who stick their necks out, don't hedge and use data. Linzer is a star.

4 comments:

Donnie Berkholz said...

Silver is a funny case because his mode is actually right on the money, just not the average.

Simon Wardley said...

Ah, so his prediction was close but not right then?

Whereas Drew Linzer might have hit the nail on the head?

Donnie Berkholz said...

Well, Silver was right in a way, but he, and other quants, get to make multiple guesses depending on how people treat wrongness. You could argue that his calculation was right but his interpretation of the results was not. The most likely single result from his calculations was 332-206, and the median was likely close to that as well, but he instead chose to take the mean.

http://www.huffingtonpost.com/simon-jackman/pollster-predictions_b_2081013.html actually has a really nice description of the various approaches to loss functions, and therefore choices of a single number.

Simon Wardley said...

Nate Silver's prediction was impressive but he hedged ... he took the average of a range of possible results.

Still, it was impressive.

But not as impressive as Drew who just picked the right result.