July 1, 2004

Contact:
Elaine Justice, 404-727-0643, ejustic@emory.edu
Deb Hammacher, 404-727-0644, dhammac@emory.edu

Presidential Polling Offers Limited Perspective

Trying to precisely predict the outcome of this year's presidential election based on the current crop of polls is the equivalent of reading tea leaves--and about as accurate, according to Patrick Noonan, an expert on polling and decision analysis at Emory University's Goizueta Business School.

"The race is clearly a dead heat at this point. What's interesting now, because the country is so evenly split, is that it highlights the inaccuracies and limits of polling in tight races," Noonan says. "The only thing the polls definitively show is that we are closely divided as country."

In such a close presidential race, deviations in what the polls report are usually due to margins of error, which can greatly affect accuracy, Noonan explains. Polls also can vary widely in their methodologies and how their representative samples are drawn, both factors in how results are tabulated.

"The polls seem to show a horse race with a lot of action, with approval ratings or possible votes for Kerry going up, or Bush going up and down, but there's really nothing there. It's just statistical jitter," Noonan says. "When the numbers blip up and down, people tend to wonder 'What happened yesterday to move Kerry or Bush up two points? What influenced it?' The answer is likely that nothing happened at all."

For example, the CNN/Gallup/USA Today May 23 poll reported Bush with 47 percent of the potential vote and Kerry at 49, and the June 23 survey showed Bush at 49 and Kerry at 48. "It would be easy--but incorrect--to conclude that Bush has gained two points," Noonan says, because the random samples of about 1,000 people . result in a statistical margin of error of 3 or 4 percentage points.

Noonan is an associate professor of decision and information analysis. He can be reached at 404-727-0549, or Patrick_Noonan@bus.emory.edu.

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