Rasmussen and Gallup Still Lagging Behind Other Polls

[babylonsister]

http://www.openleft.com/showDiary.do?diaryId=7381

Rasmussen and Gallup Still Lagging Behind Other Polls
by: Chris Bowers
Thu Aug 07, 2008 at 11:00


Two weeks ago, Alan I. Abramowitz pointed out a significant statistical discrepancy between the Gallup and Rasmussen daily tracking polls, and all other national polls on the presidential campaign:

Here's what I found. Since the beginning of May, over 74 days of polling, the Gallup tracking poll has shown Barack Obama with an average lead of 1.6 percentage points over John McCain. During the same time period, the Rasmussen tracking poll, over 76 days of polling, has shown Obama with an average lead of 1.8 percentage points. But during the exact same time period, 38 other national polls have shown Obama with an average lead of 5.2 percentage points.

Abramowitz's data was through July 21st. Given that this discrepancy continues to persist, I thought I would update it. From July 22nd through today, there have been forty-five national polls. Thirty-four of these polls were from Gallup and Rasmussen (although one was not a tracking poll), while eleven were from other polling firms. I found virtually the same discrepancy as Abramowitz.

I have no explanation for this difference. I also don't intend to pick sides, as there is an awful lot of data in both camps here. As per usual in my polling analysis, my feeling is that the truth probably lies somewhere in between, rather than on one end or the other.

However, I think this difference does actually explain something else. There is a long running debate in this presidential campaign as to whether it is a toss-up, or whether Obama holds a statistically significant (though not statistically overwhelming) lead. This polling discrepancy is, I believe, the source of the debate. The overwhelming number of polls put out by Gallup and Rasmussen are skewing the polling picture against Obama on at least an intuitive level. These two polls dominate the political junkie consciousness on the state of the campaign, and even dominate the averages in the campaign because they are so numerous. As such, people following the campaign closely are drawn to believe that we are more in the toss-up range. However, if all polling firms were weighted equally, Obama would hold a statistically significant advantage of around 3.5%-4.0%.across about a dozen polling firms, instead of the 2.0-3.0% lead he holds according to Pollster.com right now.

My thesis is that Gallup and Rasmussen spam are causing the campaign to appear about 1-2% closer than it probably actually is. While 1-2% isn't a very big difference in terms of actual numbers, it is the difference between a toss-up and a small, but statistically significant, lead for Obama. And that is actually a big difference.

To see all the polls, go to link~

[FrenchieCat]

1. Polls are part of the tool kits of the News propaganda machine.....

[ObamaIL]

2. Anyone Know How these Tracking Polls Work

I know they're conducted daily and average a certain amount of days...at least that's my understanding.

So today's poll shows really what the last 3 days of polling show. They end up with a fairly decent sample size, I don't get why they're different.

[RichardRay]

3. I'd be surprised if the polls came out the same

At least until things get much clearer closer to the election. Each of the polling organizations uses different methodologies, differing sampling technique, different survey design and different statistical approaches to analyzing the data. They do that because they're businesses trying to differentiate their products in the marketplace.

As long as each pollster uses the same methodologies from day to day and week to week I have no quibble with their results. I may or may not believe them, but I don't choose to call them liars and tools, just wrong. I do get suspicious when a pollster makes a methodology change without announcing or explaining it, but that's what 538 is for. The polling junkies over there catch that stuff very quickly.

Don't get paniced about the polls and public opinion; doing so confuses the horse and the cart. Except for junkies and members of the scribbling classes the polls reflect estimates of public opinion, they don't create it.

[ObamaIL]

4. Thanks

I've been to 538 before but not recently. Sometimes MyDD but I haven't been there much either since one of their guys was so anti-Obama and pro Hillary.

I'll be sure to check out 538.

[Drunken Irishman]

5. It's because they're tracking polls. Tracking polls generally are 1-5 points off static polls.