Posted on 08/25/2016 8:25:03 AM PDT by usafa92
I’m tired of hearing about the poll from Donald Trump fans such as Reince Priebus, Matt Drudge and Donald Trump himself.1There’s nothing wrong with being your own No. 1 fan! They frequently cherry-pick that poll because it consistently shows much better results for Trump than the other surveys. As of Tuesday morning, for example, the poll showed the race as virtually tied — Hillary Clinton 44.2 percent, Trump 44.0 percent — even when the national poll average has Clinton up by about 6 percentage points instead.
This has been a fairly consistent difference between this poll and most others. Take the LA Times poll, add 6 points to Clinton, and you usually wind up with something close to the FiveThirtyEight or RealClearPolitics national polling average. What’s the source of the LA Times poll’s Trump lean? There are good “explainers” from The New York Times’s Nate Cohn and Huffington Post Pollster’s David Rothschild. Long story short: The poll’s results are weighted based on how people said they voted in 2012. That’s probably a mistake, because people often misstate or misremember their vote from previous elections.2In particular, it’s likely that more people say they voted for the winner than actually did. Imagine, for example, that respondents in a poll claim they voted for Barack Obama by 10 percentage points, when he actually beat Mitt Romney by 4 percentage points. The LA Times poll will conclude that it has too many Obama voters, most of whom are also Clinton voters, and therefore downweight Clinton’s numbers. But some of those Obama “voters” actually voted for Romney or sat the election out.
The poll does some other things differently also, some of which I like. For instance, it allows people to assign themselves a probability of voting for either candidate instead of saying they’re 100 percent sure. And the poll surveys the same panel of roughly 3,000 people over and over instead of recruiting new respondents. That creates a more stable baseline and can therefore be a good way to detect trends in voter preferences, although it also means that if the panel happened to be more Trump-leaning or Clinton-leaning than the population as a whole, you’d be stuck with it for the rest of the year.
But I’m also tired of hearing from the LA Times poll’s critics. I’m not a fan of litigating individual polls, for several reasons. First, in my experience, these critiques tend to involve their own form of cherry-picking. Clinton fans will pick apart the LA Times poll and find a few things wanting — in this case, with good reason (in my opinion). But they’ll give a free pass to a poll like this one that shows Clinton ahead by 16 percentage points in Virginia, even though it’s also something of an outlier. You can almost always find something “wrong” with a poll you don’t like, even if you might have approved of its methodology before you saw its result.
It’s probably also harmful for the profession as a whole when poll-watchers are constantly trying to browbeat “outlier” polls into submission. That can encourage herding — pollsters rallying around a narrow consensus to avoid sticking out — which is bad news, since herding reduces the benefit of averaging polls and makes them less accurate overall.
Furthermore, the trend from LA Times poll still provides useful information, even if the level is off. Before the conventions, the poll had Trump ahead by an average of 2 or 3 percentage points. Trump then got a modest convention bounce in the poll and pulled ahead by 6 or 7 percentage points. But Clinton got a bigger bounce, and she’s been ahead by an average of 1 or 2 percentage points in the poll since the conventions, although it’s been a bit less than that recently, with Trump narrowly leading the poll at times. All of this follows the trend from other polls almost perfectly, as long as you remember that you have to shift things to Clinton by about 6 points.
And that’s pretty much what FiveThirtyEight’s forecast models do through their house effects adjustment. A pollster’s house effect is a persistent lean toward one candidate or another, relative to other polls. House effects are not the same thing as statistical bias — how the poll compares against actual results — which can be assessed only after the fact. Nor do they necessarily indicate partisan bias. For example, Public Policy Polling, a Democratic polling firm, has a very mild pro-Trump house effect this year.
Calculating house effects is simple, in principle — you compare a poll’s results against the average of other surveys of the same states (treating national polls as their own “state”). In practice, there are a few challenges, which you can read more about in our methodology primer. One of the important ones is defining what the average is. In the case of FiveThirtyEight’s forecasts, the average is weighted based on our pollster ratings.
Put another way, the house effects adjustment seeks to determine what the best pollsters are saying and not just what the most prolific ones are saying. In 2012, that made a difference: the higher-quality pollsters generally projected better results for Obama than the lower-quality ones. This year, any such effects are very minor. Although they may be increasing, with traditional telephone polls tending to show better numbers for Clinton recently. and neither Trump nor Clinton benefits much from the house effects adjustment overall, although it can matter more in individual states. Polls in Nevada happen to be a Trump-leaning bunch, for instance, so the house effects adjustment slightly helps Clinton there.
Nate was right in 2012.
But he hasn’t been right about Trump even once.
So do we leave the UPI/CVoter daily presidential tracking poll alone too? lol
People coming out of slumber to vote again or for the first time do not figure to Nate. Neither do democrat cross-overs.
Nate was only right because he had polling straight from the Obama people lol
Jealousy?
Silver decries messing with polls, and then he says to add 6 points to this poll.
What a numbnutz.
A stopped clock is correct twice a day.
Little Nate was correct once.
“Still haven’t figured out why the enlightened jews in this country hate Trump so much.”
Enlightened? They left Judiasm when they popped ot of the womb. They are all Capos, like George Soros, who worship their wallets and Socialism/Marxism. They would finance the Nazis today! It’s almost as though the only “real Jews” left in the world today are in Israel, and they are there without any support from their “brothers and sisters” living in America.
“people often misstate or misremember their vote from previous elections.”
[citation needed]
Silver totally blew the 2015 British general election polling too, FYI.
Prediction:
The polls will converge as we get closer to Election Day. The Nate Silver Projections and these polls will grow closer and closer to the USC Poll as we move through September and October. Nate Silver will stop talking about his phony 6 point “error” in the USC Poll.
By the night before Election Day we should know who is going to win. I think it will be Trump. Hope I’m right.
The methodology of the USC poll might be considered experimental, but we are in an age of experimental polls.
In the old days, you’d call (landline) phones. Today, you simply have to also call a certain percentage of cellphones, or else make some other adjustment for the fact that a lot of people today don’t have landlines. Among the phone-based polls are some that use an automated voice and others that use a live caller. Also, the length of the interview varies greatly. I know a poll-taking firm that buys lists of registered voters with all the demographic information pre-coded. His interviews consist of 3 to 5 questions, and take only a minute or so. Some other interviews take 20 to 30 minutes to complete. You get very different results, nowadays, in live-caller versus automated-caller polls, and in long interview polls versus short interview polls.
Along with phone-based polling, there is “internet” polling. Firms assemble “panels” of respondents, and recurrently ask questions of them. Basically, the same pool of people are asked, and asked again repeatedly through the course of a year. The firms try to keep the pools representative of the American population, but mostly they rely on weighting responses by demographic data.
The USC poll is of the second variety, with some twists unique to it. As to whether it has a bias as compared to the polls that Nate Silvers likes, isn’t the real question. The real question is why do live-caller polls favor Hillary by an average of something like 6 points, relative to automated-caller polls?
What I find interesting, is that no one knew where Silver was getting his data.
Yet he called every state exactly.
It’s almost as if he were given the answers in advance of the test.
Because they are not enlightened.
I guess he doesn’t like the UPI poll either (Trump +1), or the YouGov poll (Clinton +3), or the Zogby poll( Clinton +2). I’m sure he despises the Pew poll (Clinton +4).
Poor Nate is running out of polls to use.
Uh I’m a Jew and pretty enlightened! You are obviously talking about the guilt ridden, self loathing or once a Dem always a Dem Jews who are of the same herd mentality as black Americans.
Personally I don’t understand how a group of fairly educated and self sufficient people can vote democrat period but some mysteries are beyond comprehension:-)
The idea that people tend to remember voting for the winner comes from the results of the polls themselves. When polled, a higher percentage of people claimed to have voted for the winner of the previous election than what the actual results were. The author seems to interpret that to mean people either don’t remember or they are lying. It never occurred to him that people who voted for the loser in the previous election are less likely to participate in a poll.
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