11-01-2012, 08:17 AM
I was doing some research and came across your thread - and figured I might give you some feedback disputing your allegation that pollsters are "oversampling" Democrats.
First, most polling outfits don't "weight" for party affiliation.
You stated (in your first post):
But that is inaccurate. What was at the bottom of that link was a question where they asked the respondents how they self-identified.
The poll didn't weight them that way, that's just what they were.
Pollsters do statistically adjust (weight) for certain factors: region, age, ethnicity, etc. - but most don't make adjustments for party identification.
Pew has a good rundown of this: Party Affiliation and Election Polls
And they state their case plainly:
To make the argument that a particular poll is "skewed" because the party identification is "incorrect" (i.e. hasn't been weighted) introduces exactly the bias you (or someone making that argument) has argued against.
Of course this isn't true for all pollsters. Some do weight by party ID (Rasmussen, in particular). And that does lead to a problem. Suddenly you are comparing apples and oranges.
If you look at Rasmussen (which does weight for party ID), and compare them to a bunch of pollsters that don't weight for party ID, you're going to think that most polls are oversampling Democrats - when in actuality they are simply reporting what their respondents are telling them.
It's telling that your graph(s) look(s) eerily similar to this one:
(From this article: Why weighting polls for party identification is wishful thinking )
But as the author of that piece states:
Which as the author states, tends to reinforce the fact that there is no real relationship.
And lastly, the final argument against supposed party ID skewing comes from this article:
No, The Polls Aren't Oversampling Democrats
The author sums it up:
Go check it out for yourself at: Party Identification - Adults
It pretty well backs up the final author's point.
I think it's interesting that so many people are, in effect, raging against the machine right now. But if you are a realist, then you have to agree that pollsters do what they do to make a profit. Most of them release these political polls on their own dime (i.e. they aren't commissioned, and thus there is no customer, per se). They are basically giant commercials for their primary business (polls commissioned for profit from businesses) or for their university (visibility). Thus they have a huge incentive to be accurate. And that alone should give you pause when considering whether a large percentage of pollsters would do something detrimental to that goal.
If someone is holding out hope that these polling firms are all so out of the loop, and thus biased against one candidate over another, then that probably says more about the biases of that individual than it does about the biases of any set of polling firms.
First, most polling outfits don't "weight" for party affiliation.
You stated (in your first post):
Quote:If we look at a recent (10/13/12) Washington Post poll, where Obama has a 3 point lead over Romney, we see the following weighting (at the bottom of the link):
Democrat: 35%
Republican: 26%
Independent: 33%
But that is inaccurate. What was at the bottom of that link was a question where they asked the respondents how they self-identified.
The poll didn't weight them that way, that's just what they were.
Pollsters do statistically adjust (weight) for certain factors: region, age, ethnicity, etc. - but most don't make adjustments for party identification.
Pew has a good rundown of this: Party Affiliation and Election Polls
And they state their case plainly:
Quote:To put it simply, party identification is one of the aspects of public opinion that our surveys are trying to measure, not something that we know ahead of time like the share of adults who are African American, female, or who live in the South. Particularly in an election cycle, the balance of party identification in surveys will ebb and flow with candidate fortunes, as it should, since the candidates themselves are the defining figureheads of those partisan labels. Thus there is no timely, independent measure of the partisan balance that polls could use for a baseline adjustment.
To make the argument that a particular poll is "skewed" because the party identification is "incorrect" (i.e. hasn't been weighted) introduces exactly the bias you (or someone making that argument) has argued against.
Of course this isn't true for all pollsters. Some do weight by party ID (Rasmussen, in particular). And that does lead to a problem. Suddenly you are comparing apples and oranges.
If you look at Rasmussen (which does weight for party ID), and compare them to a bunch of pollsters that don't weight for party ID, you're going to think that most polls are oversampling Democrats - when in actuality they are simply reporting what their respondents are telling them.
It's telling that your graph(s) look(s) eerily similar to this one:
(From this article: Why weighting polls for party identification is wishful thinking )
But as the author of that piece states:
Quote:The graph is supposed to show that the more there are survey respondents who identify as Democrats, the bigger the Obama lead. Your eye is probably drawn to the relationship between Rasmussen (at bottom left) and every other pollster. Join the dots, and you would seem to have found a fairly straightforward relationship: more Democratic-identified respondents giving a more pro-Obama poll result.
...
The problem is that the relationship is being driven by one datapoint. Take Rasmussen out of the chart, and you get this graph:
Which as the author states, tends to reinforce the fact that there is no real relationship.
And lastly, the final argument against supposed party ID skewing comes from this article:
No, The Polls Aren't Oversampling Democrats
The author sums it up:
Quote:When the discussion is framed as “how could there be more Democrats than 2008,” it’s easy to see how the “polls are wrong” argument gained currency. But since there are actually fewer Democrats in the polls than 2008, the better question is whether it’s possible for Republicans to have lost self-identified adherents over the last four years, as well. This discussion should be framed by the recognition that the polls are pretty accurate: When assessing whether to “buy” the polls, it’s not a question of whether they match your expectations. The possibility that Republicans are moving into the independent column is an appealing explanation: it contradicts the false assumption that the polls assume a 2008-esque number of Democrats; it reconciles Romney's strength with independent voters and the Democratic-edge in party-ID; and, it happens to be consistent with the polls.
Go check it out for yourself at: Party Identification - Adults
It pretty well backs up the final author's point.
I think it's interesting that so many people are, in effect, raging against the machine right now. But if you are a realist, then you have to agree that pollsters do what they do to make a profit. Most of them release these political polls on their own dime (i.e. they aren't commissioned, and thus there is no customer, per se). They are basically giant commercials for their primary business (polls commissioned for profit from businesses) or for their university (visibility). Thus they have a huge incentive to be accurate. And that alone should give you pause when considering whether a large percentage of pollsters would do something detrimental to that goal.
If someone is holding out hope that these polling firms are all so out of the loop, and thus biased against one candidate over another, then that probably says more about the biases of that individual than it does about the biases of any set of polling firms.