Why voter surveys don't agree

To casual consumers of campaign news - and that would be most voters - the past week may have been particularly perplexing.

First the Pew Research Center, a respected nonpartisan polling outfit, showed President Bush ahead of John Kerry by just one point among likely voters nationwide. Then Gallup, another major brand in polling, showed Mr. Bush ahead of Senator Kerry by 13 points, also among likely voters. Other polls showed either a dead heat or a Bush lead, but smaller than the Gallup result.

Pollsters and experts flooded the zone with explanations: Bush's convention bounce is fading. The electorate is more volatile than previously thought. And, most fundamentally, don't read too much into any one poll. As the cliché goes, polls are just a snapshot in time - and sometimes the lens isn't quite in focus.

It's also worth noting, pollsters say, that it's still too early to come to any firm conclusions about who will win in November.

In fact, many of the voters who may well determine the outcome - those who have not locked in with a candidate - aren't fully engaged yet in the race.

"I would urge most Americans not to pay attention to polls," says Karlyn Bowman, an expert on polling at the American Enterprise Institute in Washington. "It seems to me, most of them are being done for the elites in campaigns and for journalists."

For the voter who does want to pay close attention, Ms. Bowman advises going to a polling firm's website and looking at the methodology. How big is the sample? Over how many days was a poll taken? Do they weight for party identification, and if so, how? She also advises looking at the trend over time within one polling organization - and not to compare among different polls.

It's also debatable whether polls can become self-fulfilling prophecies. That is, if there's a major poll showing one candidate down by a significant margin, will that discourage his voters to the point where some may think it's not worth their effort to turn out?

While there's no statistical evidence to prove that this happens in America's long-drawn-out elections, campaigns don't want to take any chances.

The Kerry campaign has played down the latest Gallup poll, calling it an "outlier." In a conference call with reporters last Friday, Kerry pollster Tom Kiley looked at the seven polls released over recent days - including his campaign's own poll, which showed the president up by four points - and came up with an average that shows Kerry not doing badly.

"If we do not include the Gallup survey, the average of all these polls points to a two-point race, with the president ahead by two; obviously it's a very tight race," Mr. Kiley said.

From the Bush perspective, while a huge lead in any poll is welcome news, it's also not in the campaign's interest to buy into a message of "we're way ahead." All along, a Bush-team mantra has been that this race will come down to the wire, and the base must remain energized. The president can't win if his supporters become overconfident and stay home on Election Day.

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