Tracking Polls 101

Tracking the Tracking Polls
Here are today's tracking poll results (all data based on LVs, Rasmussen data include leaners):

Rasmussen: tie (49-49) from +3 Bush (50-47) 2 days ago
WP/ABC: +1 Bush (49-48) from +4 Bush (50-46) 2 days ago
Zogby: +2 Bush (48-46) from +2 Bush (47-45) 2 days ago
TIPP: +4 Bush (47-43) from tie (45-45) 2 days ago

So Bush's position is either weakening, strengthening or staying about the same. That certainly helps clear things up.

One is tempted to say movement in these polls can't possibly be providing much meaningful information on the state of the race.

Alan Abramowitz expands on this idea in his characteristically lucid fashion below:

For many political junkies, including myself, following the presidential tracking polls has become a daily obsession. We wait with bated breath each morning for Zogby to release his latest results. At the stroke of noon, we log onto the Rasmussen website to get our second daily fix. Finally, at 5 p.m. we eagerly await the latest update on the Washington Post/ABC News tracking poll. Some of us have even discovered a fourth tracking poll, done by an organization called TIPP (the TechnoMetrica Institute of Policy and Politics). The TIPP tracking poll usually releases its daily update sometime in the afternoon.
Tracking polls are different from other political polls. Most polls are done over several days to allow time for multiple attempts to reach those who do not answer their phone the first time. In contrast, in the case of tracking polls, all interviews must be completed the same day so callback attempts are limited or nonexistent. These daily samples are combined over three or four days, with the most recent day’s interviews added to the sample and one earlier day’s interviews dropped from the sample. The result is a kind of “rolling sample” that, theoretically, tracks day-to-day trends in support for the candidates.

Political campaigns have long used tracking polls to gauge voter response to the campaign and formulate strategy. In recent years, however, a number of media outlets have also been conducting tracking polls and reporting their results to the general public. Four years ago, for example, the Gallup organization conducted a tracking poll during the final month of the campaign. However, the results were so controversial that Gallup dropped its tracking poll this year. The problem with the Gallup tracking poll was that its results gyrated wildly from week to week, and sometimes even from day to day.

In order to avoid the kinds of problems that affected the Gallup tracking poll, the four tracking polls being conducted this year all weight their nightly samples based on certain assumptions about the demographic and partisan composition of the electorate. The result is that this year’s tracking polls have been much more stable than Gallup’s 2000 tracking poll. And all of the tracking polls have produced similar results. On average, during the month of October, President Bush has had a lead of 1 percent in the Zogby tracking poll, 3 percent in the TIPP tracking poll, 2 percent in the Rasmussen tracking poll, and 3 percent in the Washington Post/ABC News tracking poll. Since October 12th, when TIPP joined the other three, the daily average of the four tracking polls has ranged from a 1 point lead for Bush to a 3 point lead for Bush with no evident trend.

So does it make sense to monitor the daily movements of these tracking polls? The answer is that if you’re hoping to learn something about real trends in support for the presidential candidates, it probably doesn’t make sense. That’s because there is no correlation between the day-to-day movements of the four tracking polls. In other words, they don’t move together—each poll’s movements are unrelated to all of the other polls’ movements. For example, the average correlation between the daily movements of the Zogby Poll and the daily movements of the other three polls is -.18. The average correlation for the Rasmussen Poll is -.07, the average correlation for the TIPP Poll is -.09, and the average correlation for the Washington Post/ABC News Poll is -.12. The combined average for all four tracking polls is -.11. These weak negative correlations mean that there is actually a slight tendency for the polls to move in opposite directions.

What these results indicate is that the day-to-day movements of the tracking polls are essentially random. Rather than reflecting real shifts in voter preferences, the day-to-day movements of the tracking polls are simply reflecting sampling error. This doesn’t mean that the overall results of these polls are wrong. In fact, the average margin between George Bush and John Kerry in the tracking polls has been very close to the average margin in other recent national polls. It just means that the day-to-day shifts in the tracking polls are probably not real and that the real level of support for George Bush and John Kerry within the electorate has not changed over the past few weeks: the presidential race has been very close since the beginning of October and it is likely to remain that way until Election Day.

So relax political junkies. Stop obsessing over the daily movements of the tracking polls and get a life! Follow the World Series. Follow your favorite college or professional football team. Follow the weather report. Follow something that is more real than the day-to-day movements of the tracking polls.


Words of wisdom from the good Professor. Heed them well and you'll get through the rest of the campaign with a considerably lower stress level.

Posted by Ruy Teixeira at 05:16 PM | link | Comments (8)


The State of the Race With 9 Days to Go
By Alan Abramowitz

There have been 35 national polls released since the first presidential debate, not

The numbers in your post are a couple of days old I think...

Kerry's up in ABC/WP and Zogby has Bush only up by 1 today...

The "How Can Gallup........" Game (Florida Edition)

Gallup has just released a new Florida poll that has Bush ahead of Kerry by 9 points among RVs (8 points among LVs). This extraordinary result has led DR reader Lawrence Becker to propose another round of the "How Can Gallup....." game. Remember how to play? It's easy! Just take the latest Gallup outlier and compare it to other publicly available data that seem to contradict it. And let the fun begin!

Here's Becker's contribution:

How can Gallup have Bush up by only 2 among registered voters nationally, yet have Bush up by 9 among registered voters in Florida?
That is really a feat. Let’s compare with some other polling organizations that poll both nationally and in Florida. Yesterday Rasmussen (by no means a Democratic firm) had Kerry up by 2 points nationally; in fact, it was Kerry’s first lead in Rasmussen’s tracking poll since August 23. Rasmussen also had Kerry and Bush tied in Florida. And Zogby had Bush up by 3 in his national tracking poll yesterday. But he had Bush up by just 1.2 points in Florida!

I'm sure you can think of your own. And here's a couple of my own contributions.
How can Gallup have the race dramatically tightening on the national level since its late September poll--from an 11 point Bush lead in their 3-way RV matchup to a mere 2 points today--while they have Bush's lead in Florida nearly doubling over the same period from 5 to 9 points?

How can Gallup have an 8 point (!) Republican party ID advantage in both their LV (44-36) and their RV (43-35) Florida samples, when the Democrats had a 2 point advantage among actual Florida voters (40-38) in the 2000 election? (Thanks to Steve Soto for the Gallup Florida party ID numbers.)

(snip)
http://www.emergingdemocraticmajorityweblog.com/donkeyrising/