IT SEEMS LIKE A NEW presidential election poll is released every three days. Do the numbers mean anything? “In the right hands, a poll is a really useful tool,” explains Missouri City native Paul Begala, a veteran political consultant who is a co-host of CNN’s Crossfire, “but in the wrong hands, somebody is going to get hurt.” Put another way: Assuming the numbers you’re seeing came from a professional pollster—and not your buddy Bob handing out a survey at the mall—they can provide a useful snapshot of how the nation is feeling. Collected over time, they show trends. But watch out for pundits, who don’t always interpret them correctly.
How so? For one thing, commentators sometimes place too much emphasis on single-poll, head-to-head results. In the past few weeks, you’ve probably read or heard something like “A new Gallup poll shows George W. Bush leading John Kerry among registered voters 53 percent to 47 percent,” followed by some analysis of why Bush is pulling away or what those numbers mean for Kerry’s election chances. But to any sensible political strategist, the results of one week’s horse-race poll don’t mean anything.
Why not? First, because head-to-head numbers are meaningless until the defining moments of a campaign—debates, conventions, battleground bus tours—have had a chance to influence the decisions of swing voters. Case in point: Michael Dukakis held a seventeen-point lead over George H. W. Bush following the Democratic convention in 1988. Oops. Second of all, a national head-to-head poll tells you only about the popular vote, not about the state-by-state allocation of electoral votes (ask Al Gore). But perhaps most important, the numbers from a single poll are potentially full of errors.
What kinds of errors? Polling firms typically survey a representative sample of the electorate over the phone—say, a thousand people (the number is posted in most news articles). That strategy is accurate only if the survey is truly random, meaning every citizen has the same statistical chance of being contacted. But even if the pollsters use advanced random-digit dialing