Perhaps the Democratic skew this year was the result of picking the wrong precincts to sample? An easy explanation, but not true. A post-election review of these precincts showed that they matched the overall returns. Whatever produced the pro-Kerry tilt was a consequence of something happening within these precincts. This year, it seems that Bush voters were underrepresented in the samples. The question is, why were they missed?
Mitofsky, the veteran pollster who co-directed this year's exit surveys, fears that Republican voters refused to be interviewed in disproportionately higher numbers, thus skewing the results. Perhaps they were busier than Democrats and didn't have time to be interviewed. Perhaps they disliked the media's coverage of Bush, and showed it by snubbing poll interviewers. Whatever the reason, Mitofsky warned the networks about the apparent Democratic bias mid-afternoon on Election Day -- a caution "they chose to ignore," he told Terence Smith on PBS.
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If the snubbing theory is confirmed, it would not be the first time that Republicans are believed to have just said no to exit pollsters. Historically, exit polls have been more likely to err on the side of Democratic candidates, though this bias is usually small. In 2000, for example, the exit polls overstated Democrat Al Gore's share of the vote by more than one percentage point in about 20 states, while inflating Bush's share in just 10 states.
The relatively small number of precincts sampled nationally and in each state create other, subtler problems. While 50 precincts may be sufficient to accurately characterize the overall vote in a large state, it increases the odds of missing or under-representing the views of smaller subgroups. For example, the Florida exit poll in 2000 found that Bush and Gore equally divided the Latino vote statewide -- a finding doubted by many academics. They noted that the sample of precincts in that state did not account for heavily Cuban American neighborhoods in Dade County -- and thus missed precincts that went heavily for Bush. This year, the national exit poll finding that Bush captured 44 percent of the Hispanic vote, up nine points from 2000, also has been challenged over sampling issues.
There are questions that are more difficult to answer. How do we know the demographic splits are right? We assume they are because one key feature of exit polls is that the results of the completed survey are weighted to reflect the final actual vote. This adjustment has the effect of fixing a number of other, smaller problems created by under- or over-sampling support for one candidate or the other.
But weighting may not fix all the problems. For example, one question in the 2004 exit poll asked people to rate their feelings toward the candidates. What if enthusiastic and angry voters disproportionately agreed to participate in the poll while those less emotionally engaged said no? The result would incorrectly suggest an emotionally charged electorate; weighting the data does nothing to fix this problem.
That final weighting also is central to the controversy over real or imagined electoral irregularities. It's true that exit poll results available on CNN and other networkWeb sites late into election night showed Kerry with that now-infamous three percentage point lead, an advantage based exclusively on exit polling and a pre-election survey of absentee voters. When those survey results were statistically adjusted in the wee hours of Wednesday to reflect the actual vote, Bush suddenly -- and seemingly mysteriously -- jumped into the lead nationally and in several key, closely contested states.
But this sort of final adjustment is done on every exit poll. Most of the time, it doesn't matter because there's a clear winner, and the numbers move up or down slightly while the order of finish remains the same. But because this election was so close, the weighting had the effect of flipping the winner and igniting the fevered imaginations of the Michael Moore crowd.
Compounding and amplifying the exit poll woes this year was that the first wave of results, available moments after 1 p.m. on Internet Web sites everywhere, shaped the way journalists were thinking, at least through much of the afternoon and early evening. The first rounds exert a particularly strong influence on broadcast journalists because they use them to develop story lines ("Kerry won a majority of female voters, but Bush did better among women than he did four years ago . . .") before the evening news.
Last Thursday, the National Election Pool board took steps to minimize this problem next time. It voted to delay release of the first wave of exit poll results until after 4 p.m. That may or may not minimize the damage done by bloggers because those numbers will still leak out and cause mischief. Ironically, the first release of data shortly before 1 p.m. that showed Kerry leading by one point was closer to the final result than the 3:50 p.m. release, which showed the Democrats leading 51 percent to 48 percent. That doesn't mean the early release was more "accurate." Early data are not necessarily a reliable predictor of the final outcome because different types of voters tend to cast ballots at different times of the day.
In a perfect world, early exit poll results would be treated just like early vote returns or the score at the end of the first quarter of a Redskins game. In a gubernatorial contest, the news media have learned not to get too excited about early returns from, say, Northern Virginia; we know from experience and common sense that partial returns from a fraction of the electorate are an unreliable guide to the outcome.
Sometime soon, I suspect that the electorate will come to see these early exit poll results the same way. The view of exit polls also will change, from blind awe and acceptance to respect tempered by a healthy skepticism. Thanks to the 2004 election and my new best friends the bloggers, we're closer to that day.
Richard Morin is The Post's director of polling and writes Outlook's Unconventional Wisdom column. His experience with national exit polling goes back to the 1988 presidential campaign.