Articles and Analysis


Battleground Drops Party Weighting

Topics: Age Weighting , Party Identification , Party Weighting

We missed doing a "poll update" on the GWU Battleground Poll today, partly because we did not receive the usual PDF via email with the daily results. The results flipped on that survey flipped today from the 1-2% lead that they had been showing for John McCain for the last seven releases to a two-point Obama advantage (48% to 46%).

2008-09-28 battleground.jpg

The difference is explained at the bottom of the slide in the PDF. "On 9/29 - Weighting changed from Party ID, Race, and Age to Race and Age." So according to the graphic, they stopped weighting by party identification on today's release. Does that explain the reversal in vote preferences? By all appearances, it does.

I talked separately today to both Republican Ed Goeas earlier today, and his Democratic counterpart Celinda Lake, the two pollsters who oversee the Battleground survey. Goeas explained that their party weights had held Democrats to a three-point advantage on the initial party ID question ("Generally speaking, do you think of yourself as a Republican, a Democrat, or an Independent?"). With the party weight removed, he said, Democrats now hold a seven point advantage on party identification. With the party leaners included, Goeas said, the Democratic advantage grows to 9 points.

Goeas also said that removing the party weight had the effect of changing the age distribution. It increased the weighted value of respondents between the ages of 18 and 34 from 17% to 22% of their sample.

Last night, Nate Silver flagged the age of the Battlegound survey as a likely explanation for the fact that, until today, only the Battleground survey showed John McCain with a greater percentage of the national vote than Barack Obama. Nate was right to question the relatively small number of younger voters in the sample. He pointed out that the U.S. Census Current Population Survey (CPS) showed 18-to-34-year-olds as a larger percentage of the voters in 2004 (23.8% -- while Silver imputed a slightly higher value, this spreadsheet on the Census page he linked to allows for a calculation of the more precise statistic).

In my National Journal column, set to appear tomorrow, I'll have more thoughts on the issue of weighting by age. The quick version is that while there is no ideal "right" answer for the age distribution of the electorate, the CPS estimates from 2004 are not a bad place to start.

"The real issue," Celinda Lake explained by email, "is the turnout model." She continued (link added):

I believe there will be heightened youth turnout and our work together for Rock the Vote and our internal polling has shown heightened youth interest and turnout. I believe we have been underestimating the youth turnout with a traditional, conservative turnout model. We have moved to a model with higher youth turnout ans well as looking at age in the weights.

Bottom line: The change in the Battleground weighting today most likely accounts for their net four-point shift on their survey in Obama's favor. I'll have more details tomorrow when my column is posted.


Mark Lindeman:

"Goeas also said that removing the party weight had the effect of changing the age distribution. It increased the weighted value of respondents between the ages of 18 and 34 from 17% to 22% of their sample."

That's counterintuitive if they used the same age weights before and after removing party. It could be because the age weights are applied to the whole sample, while the reported results are for LVs only. So, lessee, their sample of young voters included lots of eager Democrats and less eager Republicans, so applying the party weight (before the LV filter, whatever it is) had the effect of reducing expected turnout among young voters, and removing it therefore had the effect of increasing the youth share of the electorate?

Or maybe something else happened. I think Mark B. should eventually write an article: "When Weights Attack!"



18-34 year olds may make up 23.8% of the population but they certainly don't make up 23.8% of the vote. Did n't Democrats think youth vote was going to win it for McGovern? Besides, churches and Christian universities, particularly in swing states are mobilizing their young people to vote McCain. members of the military in swing states who are 18-34 are more likely to vote McCain. First of all, it's really only a few states that matter. Second of all, the Republican and Military youth vote is being mobilized in swing states as well. Does it really matter how many young people are mobilized to vote for Obama in California, NY, Illinois etc? No it doesn't matter one little bit.

Lets see some breakdown of likely youth vote with Party affiliation in swing states.



To s.b.

In 2004 election, the turnout of 18-34 was 24 percent.
You can check the link below.



While it's supposedly a bi-partisan effort, I find it interesting that Tarrance is actually the contact (and presumably producer) of this poll. On at least an anecdotal level, this confirms some of the issues with partisan poll biases. I agree that party ID is a relatively stable metric and that we should look at it to make sure election polls don't go out of whack. However, we lack a parametric benchmark. So, while partisan pollsters do try to "get it right," it's fascinating that their view of the electorate's party ID reality appears to be at least a tiny bit skewed in their own party's favor.



I think that the youth vote is becoming highly mobilized in this upcoming election. Largely, young people don’t vote because they do not feel that their vote matters. This disillusionment of democratic principals is something I’ve heard repeated again and again on my college campus. When registering voters I’ve witnessed scores of young people quickly nodding that they have registered to vote, when clearly they have not. But can we blame them? My education has taught me the values of voting, voicing my opinion, and my ability to change the world, and yet I’ve seen very little of it in action. The Iraq war has presented us with many of the same fears and problems as Vietnam, and the threat of a draft is ever permanent. I’ve seen many friends of mine drop out of college because they cannot afford to continue. Public schools are still under funded. Gay rights are continuously ignored. Racism and classism is still ever present in our culture. My right to have an abortion is still being debating, and becoming closer and closer to no longer becoming an option.

To me, it seems like a chicken and egg problem. Youth agenda is unimportant and under represented so we don’t vote, we don’t vote so our agenda isn’t represented. However, I can still retain hope that this election might change things. I’ve seen many young people who plan on becoming more aware and involved in the political process. However, I’m afraid I believe the burden falls on our parents and grandparent’s generation. When push comes to shove if you want us to care, the first step is proving that things will change. That if we vote, care and work we can put someone in power that cares about issues that effect us now and in the future.

Maybe I’m still just bitter having my heart broken for the first time when I was sixteen by John Kerry in 2004.



I'm 24 year old male in ct and have been following politics for over 2 years now VERY closely. I probably have learned and retained more political knowledge over these 2 years than the average 40 year old and I'm not the only person my age i know like this. I listen to news/talk radio over 5 hours a day, watch network news shows for at least 2 hours in the evening and then go online to do this stuff later at night.

We are mobilized, we are ready, we will show.


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