Slashdot Mirror
Math Indicates Pollster Is Forging Results
An anonymous reader writes "Nate Silver suggests the political pollster Strategic Vision is 'cooking the books. And whoever is doing so is doing a pretty sloppy job.' Silver crunched five years worth of their polling data, and found their reported results followed a suspicious pattern which traditionally suggests fraud. The five-year distribution of the numbers 'is not random. It's not close to random.' The polling firm had already been reprimanded by the American Association for Public Opinion Research for failing to disclose their methodology, though the firm argues they did comply with the organization's request. Their response to Silver's accusation? 'We have a call in to our attorney on this and fully intend to take action that will vindicate us.'"
a. you can't post
b. if you do manage to post, post goes to wrong topic!
In other words, do they do stuff that actually matters?
In a word, yes. Nate Silver manages the blog FiveThirtyEight and is well-known as a statistical analyst from the 2008 US election (among other things). Strategic Vision has released quite a few polls. In Silver's words,
So yes, this is pretty big news, should it turn out that Strategic Vision's behavior is in fact illicit. They're influential enough that news agencies may pick up their polling results. This is bad enough, but when you factor in the fact that polling results can be very effective propaganda in something like a presidential race, fraudulent polling can have significant consequences.
Nate Silver does great analysis at the first order multiple-linear-regression level -- he outperformed all the other polls/predictors in 2008 iirc.
He sucks at meta-analysis though, in that he just doesn't understand the math. His 2008 monte-carlo stuff gave good results, but was just a bad reinvention of averaging. His recent foray into analyzing stock returns was interesting but 0-information (i.e. useless.)
Now he's mentioning Benford's law, but playing with trailing digits. Then he handwaves a non-normal result with an appeal to "it looks wrong." Come on, give us some real math here!
That said, he's probably right, but he's given us no math to support his claim.
Take any data set and you'll find patterns that are statistically impossible.
Not if you understand statistics.
Also note: If you understand statistics you would _never_ use the phrase 'statistically impossible'
John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
Fortunately, there are corrections you can do for that. And he took a fairly normal statistical test on the numbers, which is equivalent to saying he didn't perform that many comparisons. To very rough approximation, you need to correct your p-value for all the less weird analyses you might have performed on the data instead. It's a bit hard to pin down an exact p-value for the analysis he did (the underlying data isn't expected to be flat; it's also not expected to be that bizarrely lumpy), but I promise that Nate Silver has an understanding of this issue (which you'd see, if you'd read the post).
Nope, you're looking at the webpage of a different company! See Nate's previous article:
NBC always reports on the NBC/Wall Street Journal poll. I think they commission it. They seem to do a decent job of describing how they do it:
http://online.wsj.com/article/SB124527518023424769.html
(that link works when clicked on from a Google search, but given that the WSJ has a mighty paywall, I don't know if it will work otherwise)
So maybe you need to talk about a more nuanced group than 'the media' (I wouldn't be particularly shocked if other major outfits were at least approximately as responsible).
Nerd rage is the funniest rage.
Second, if they're the same "strategic vision" that the article is talking about
They're not, from another helpful article from FiveThirtyEight
Why would you pick the name "Strategic Vision, LLC" for your company when the name "Strategic Vision, Inc." was already in use by an extremely well regarded, San Diego-based research firm that has been in business for more than 30 years? Are you deliberately trying to confuse your potential clients and leverage Strategic Vision, Inc.'s much stronger brand name?
You're looking at the page from the well regarded Strategic Vision, Inc. Funny that SV LLC seems to be so happy to sue Nate Silver, it would seem that SV Inc has a far stronger case against SV LLC.
Could be an interesting intersection of Trademark/Slander laws...
I stole this Sig
Except you've linked to the wrong company. Strategic Vision, Inc. is a well respected 30-year old polling firm in California. Strategic Vision, LLC is the shady 5-year old GOP shill corp with questionable poll results and no real office (or polling results allegedly). Careful with those links, you don't want to slander the wrong company here. I think SV Inc. may have a trademark case on their hands if their feeling litigeous.
They are a partisan, Republican-oriented polling company. They have gotten into trouble in the recent past for their questionable results.
First, the example he gives where he looks at polls from ALL sources is an example of a plausible distribution of real results because, assuming the majority of pollsters are not cooking their data, the data should be dominated by randomness. He then looks at this particular pollster and finds a much greater disparity in trailing digit frequency. The question is, is it significant, or just chance?
Given the numbers, it's not particularly hard to figure out. You can calculate the likelihood of any particular result given a theoretical distribution using a G test of goodness of fit. Technically for numbers this small you could use an exact test but I don't know of a web version and I'm too lazy to write one up. But here's a description of, and an excel spreadsheet that performs, the G test of goodness of fit: http://udel.edu/~mcdonald/statgtestgof.html
Basically, you plug in the distribution you see and compare it with the one you expected. What you get is the probability of that distribution occurring by chance. So if we plug in the observed data for all the pollsters and assume equal likelihood for all trailing digits we get a p=0.006. Whoops, looks like our assumption isn't quite correct. As the blog author notes, the observed distribution is humped a little, favouring the middle numbers. He also gives a possible explanation. For giggles, the probability of the Strategic Vision results given equally probable trailing digits is absolutely microscopic: p=1.44x10^-17. Together those tell us that our assumption of equal digit distribution is probably not quite right, but the Strategic Vision data still looks mighty funny.
Okay, so assume instead that most pollsters aren't making up their numbers. Not that their numbers are necessarily accurate, but that they're at least not making them up off the top of their heads. So using the data from all pollsters as a template, how likely is the Strategic Vision distribution? That's a G test of independence: http://udel.edu/~mcdonald/statgtestind.html. We could use Fisher's exact test, but I can't find one that will do a 2x10 table.
Plugging in the data, we get G=43.068, d.f.=9, which gives p=2.09x10^-6. The blog author was actually a little careless when he said the chances of Strategic Vision's results are millions to one against. If you insist on the equal-probability theory then the odds are 70 quadrillion to one against Strategic Vision and 166 to one against the industry as a whole. Taking the more realistic approach that the industry average is a better representation of the actual probability, the odds against Strategic Vision's results are about half a million to one against. Not millions to one, but close enough.
I hereby take back everything I said about Strategic Vision and reapply it to Strategic Vision, LLC, times two.
"Yeah, you go ahead and cling to the belief that the insurance industry doesn't want the health care bill to go through"
You are right the insurance industry would stand to gain massively by that proposal. That's exactly why the liberal sect of the democratic party has been fighting that provision.
I would like to point out that the insurance industry is being very pragmatic they have a two tier battle plan. They don't want the bill to pass however if it dose pass they want to have things like that put in
That provision was added to some of the bills to "tempt" republicans into voting for it as several Republicans have explicitly said they would like to see that included.
As far as "I'd certainly like to see some numbers regarding who the insurance industry as a whole is contributing to." The money has been flowing quite rapidly into the conservative arm of the democratic party. Ben Nelson, Mary Landrieu and Max Baucus have all goten heavy donations since this whole thing has started (from insurance companies). That is not to say that the republicans have not been getting a lot of money from the insurance companies. (That goes without saying) So to some it up Republicans are continuing to get good pay checks,(the usual) however some conservative democrats are now also getting paid for their services(Newish). Just for your info many progressives want political blood for this, Ben Nelson and Max Baucus and to a much lesser extent Mary Landrieu are the one thing that is standing in the way of progressives' holy grail. For that many of us want political revenge at any cost.
Well, you might need to explain what astroturfing is
Astroturfing is where a special interest tries to create the impression of grassroots support. That may be through paying shills to post a lot on message boards with posts that support your position, it may be through dodgy polls or it may be through other means.
note: i'm known as plugwash most places but i screwd up registering that here somehow in the past and now can't register