Posts by David Hood
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Early European artists in NZ used to comment on the Hard Light (compared to the smoggy landscapes of European). Today in Dunedin was a bright, high contrast day. This picture is from a lunchtime walk.
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Hard News: The Righteous Humour, in reply to Roger Lacey,
but today the links to them from here are broken
As of now, midday Sunday, the embedded clips in the main post are working fine from Dunedin (with no special setup).
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Hard News: The Big 2012 US Election PAS Thread, in reply to BenWilson,
I understand that problems in the underlying sims cascade into the final result.
As I understand it, a greater degree of uncertainty in the poll analysis and aggregation would, in general, produce a wider spread of potential results (this might move the 270+ percentage a bit). A mistake in the model in the way that the states results interrelate would tend to produce a massive error in results.
For a long while Nate Silver was listing Obama's chance of getting 270 seats or more as smaller than the other correct polling aggregate sites (though vastly larger than the pundits). This was because 538 was making a deliberately high estimate of uncertainty (in part because he thought for the Republicans to be that confident they might know something he didn't), so his graph of simulated results was wider and flatter. As election day approached, all the polls, and all the polling analysts, converged in their predictions.
As 538 keeps portions of his model private, we can't assess if the way the factors flow together is justified, but the uncertainty in the aggregation process is reflected in the spread of the results in possible electoral college vote outcomes, and the percentage figure is an aggregation of this spread based on the 270 threshold. I would call it a valid measure of the likelihood of Obama getting more than 270 electoral votes if the modelling process is accurate. I suspect Nate Silver would say the accuracy of his model should be judged on the results (in reality some of the open academic models were as accurate, but Nate Silver is much better at communicating with a general audience).
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Hard News: The Big 2012 US Election PAS Thread, in reply to John Armstrong,
But people only have so much time and energy to absorb information. With so much media content focusing on poll results, it surely must be less likely that the electorate is well informed about policy
I saw an echo of this concern in a BBC article on poll analysts I was reading. Writing of Sam Wang, a molecular biologist who runs one of the poll aggregation analysis sites:
Wang originally started his site in the hopes of calming some of the polling mania by providing a clear look at what the polls really said. The time spent trying to read the tea leaves, he hoped, would be better spent discussing the issues.
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Hard News: The Big 2012 US Election PAS Thread, in reply to BenWilson,
So 92% isn’t the confidence interval itself, relating to the statement “Obama gets 270 or more Electoral College votes”,
You are kind of sorta correct that it is not the case that 92% is the confidence interval. Let's try this summary of Step 7 of Nate's methodology:
From the polls (plus some in-house adjustments known only to Nate), each state race has an expect result, and some uncertainty.
Random numbers are generated of potential electoral vote on the basis of that uncertainty, and many, many, many mock elections are held (there is a bit more to this on the way the state results connect together in various ways so each states uncertainity is not independent of the other states).
Looking at every single result of the mock elections 92% of the time Obama got 270 or more of the electoral college votes, with the average number of electoral college votes across all potential electoral results 313, but the single most likely result 330 (the mode, and with Florida likely to go Democrat Nate Silver seems to have been 1 of 2 analysts I have seen who had that as the most likely outcome number).
And here is where I am pushing the boundaries of my knowledge: to some extent, the traditional idea of uncertainty and confidence don't quite apply, because the random potential outcomes are being drawn from the uncertainty, which is why Nate's major warning were systematic bias in the polls (which would be the data flowing into the final step did not correctly model the real world). Other peoples concerns were that Nate's private adjustments at earlier stages might have been biasing the outcomes.
As I write this, I've thought of another way of phrasing in in more traditional statistical terminology: Given (from the cumulative analysis of polls) a mean electoral college vote for Obama of 313, and an amount of uncertainty (let's call it the standard deviation) that we haven't been told on the 538 site, then 92% of the time Obama is going to get 270 or more electoral college votes (a critical threshold within the range of uncertainty. So in some respects, the 92% is doind a similar job to expressing a confidence interval, but it is a different thing in the finer level of detail. -
With the election results I thought Charles Darwin did pretty well for both someone English and Long Dead.
For those not aware, Georgia had a "evolution is a lie from the pit of hell" congressman running in a district so republican he was unapproved. So as a sign of protest people were putting Charles Darwin in as a write-in candidate. The only county to report the Charles Darwin vote has it at 2% of the unopposed republicans total. Which is better than the libertarians did nationally.
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Hard News: The Big 2012 US Election PAS Thread, in reply to Ross Mason,
Please don’t mention Baysian Statistics
How about bringing it up in comic form, with a very timely new xkcd
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Hard News: The Big 2012 US Election PAS Thread, in reply to steve black,
The bad news is I haven’t read Nate Silver’s methodology yet
Allow me to point you in the right direction.
That said, he has been criticised for keeping the finer detail of some of his adjustments private, unlikely some of the academic based sites, which are completely open in their processes. -
Speaker: Dreams Do Come True, in reply to izogi,
if so is there any realistic chance that it could ever happen in today’s or a future political environment
Individual states can change the process how they assign their votes (this was a ballot initiative for Colorado this year, I haven't seen how it did). What seems like is going to be the first successful outside of state reform is making the electoral college elect the president on the basis of winning the national popular vote. This is being done at through individual states signing on to the National Popular Vote Interstate Compact. It is about halfway to it's needed target.
The things are that many republicans feel that a democratic is more likely to win the national vote (which they have in recent history) so republican states aren't keen on signing up, and rural states tend to feel that it diminishes the power of their states votes (not that there are many rural states that are not republican states).
There have also been occasional attempts to make change at the federal level, such as during Nixon's presidency when an amendment getting rid of the Electoral College got through the house, but that died quickly in the Senate, let alone before consideration by the states. So, in general the likely solutions seem to be trying to work around it making the college irrelevant . -
Hard News: The Big 2012 US Election PAS Thread, in reply to Islander,
That is a scientist with deep committment to his research!
As occasional reading I am gradually working my way through the long out-of-print "Ignition! An Informal History of Liquid Rocket Propellants" by John D. Clark, which is a somewhat hair-raising memoir of the development of rocketry.
"Phil Pomerantz, of BuWeps, wanted me to try dimethyl mercury, Hg(CH3)2, as a fuel. I suggested that it might be somewhat toxic and a bit dangerous to synthesize and handle, but he assured me that it was (a) very easy to put together, and (b) as harmless as mother's milk. I was dubious, but told him that I'd see what I could do. I looked the stuff up, and discovered that, indeed, the synthesis was easy, but that it was extremely toxic, and a long way from harmless. As I had suffered from mercury poisoning on two previous occasions and didn't care to take a chance on doing it again, I thought that it would be an excellent idea to have somebody else make the compound for me. So I phoned Rochester, and asked my contact man at Eastman Kodak if they would make a hundred pounds of dimethyl mercury and ship it to NARTS. I heard a horrified gasp, and then a tightly controlled voice (I could hear the grinding of teeth beneath the words) informed me that if they were silly enough to synthesize that much dimethyl mercury, they would, in the process fog every square inch of photographic film in Rochester, and that, thank you just the same, Eastman was not interested."
