How Much Should We Trust Polls?

Sept. 20, 2008

Summary: On November 1, 2004, the day before the election, polls showed Kerry winning comfortably. The polls in 2004 all over-sampled Democratic voters in every single battleground state. There seem to be a significant percentage of people who vote Republican but either don’t like talking to pollsters or don’t have time to talk to pollsters.

Obama should listen to the “hand-wringers” in his party. Any state where polls show him with a lead of 1% to 4% should be considered a toss-up at best, or, more likely (due to the Bradley effect) “leaning McCain”.

From Rolling Stone Magazine (June, 2006):

On the evening of the [2004] vote, reporters at each of the major networks were briefed by pollsters at 7:54 p.m. Kerry, they were informed, had an insurmountable lead and would win by a rout: at least 309 electoral votes to Bush’s 174, with fifty-five too close to call. In London, Prime Minister Tony Blair went to bed contemplating his relationship with President-elect Kerry.

As the last polling stations closed on the West Coast, exit polls showed Kerry ahead in ten of eleven battleground states — including commanding leads in Ohio and Florida — and winning by a million and a half votes nationally. The exit polls even showed Kerry breathing down Bush’s neck in supposed GOP strongholds Virginia and North Carolina. Against these numbers, the statistical likelihood of Bush winning was less than one in 450,000. ”Either the exit polls, by and large, are completely wrong,” a Fox News analyst declared, ”or George Bush loses.”

But as the evening progressed, official tallies began to show … disparities — as much as 9.5 percent — with the exit polls. In ten of the eleven battleground states, the tallied margins departed from what the polls had predicted. In every case, the shift favored Bush. Based on exit polls, CNN had predicted Kerry defeating Bush in Ohio by a margin of 4.2 percentage points. Instead, election results showed Bush winning the state by 2.5 percent. Bush also tallied 6.5 percent more than the polls had predicted in Pennsylvania, and 4.9 percent more in Florida.

From Ruy Texeira’s blog (11/1/2004):

Final Pre-election Poll Analysis

By Alan Abramowitz

1. The National Polls

In the 12 most recent national polls listed on pollingreport.com, among likely voters, Bush is leading in 7 polls, Kerry in 2, and 3 are tied. Average support was 48.2 percent for Bush, 46.7 percent for Kerry, and 0.8 percent for Nader. In the 7 polls that provide results for registered voters, however, Kerry is leading in 4, Bush in 1, and 2 are tied. Average support was 47.0 percent for Kerry, 46.7 percent for Bush, and 0.9 percent for Nader. Bottom line: Even in the samples of likely voters, Bush is well below the 50 percent mark generally needed by an incumbent. In fact, when Gallup allocates the undecided vote, their likely voter sample goes from a 49-47 Bush lead to a 49-49 tie. In the broader samples of registered voters, Bush is actually trailing in most of the recent polls. With a very high turnout expected tomorrow, the registered voter samples are probably more representative of the actual electorate than the likely voter samples.

1. The Four Major Battleground States

In Florida, there have been 11 polls since October 15. Bush led in 5, Kerry led in 5, and 1 was tied. Average support was 47.5 percent for Bush, 46.5 percent for Kerry, and 1.2 percent for Nader. Turnout in the early voting has been enormous, with a clear advantage for Democrats. Expect a huge turnout tomorrow as well that will put this state in the Kerry column.In Ohio, there have been 11 polls since October 15. Kerry led in 7, Bush led in 3, and 1 was tied. Average support was 47.2 percent for Bush and 48.3 percent for Kerry. Ralph Nader is not on the ballot. Turnout is going to be enormous and two federal judges ruled this morning that Republican political operatives cannot challenge voters in minority precincts. That was Karl Rove’s last gasp in Ohio. The Buckeye state will go Democratic this year and no Republican has ever won a presidential election without carrying Ohio.In Pennsylvania, there have been 11 polls since October 15. Kerry led in 8, Bush led in 2 and 1 was tied. Average support was 46.8 percent for Bush and 48.7 percent for Kerry. Ralph Nader is not on the ballot. Pennsylvania looks solid for Kerry.

Finally, in Michigan, there have been 5 polls since October 15, including only the most recent release of the Mitchell tracking poll. Kerry led in all 5 polls. Average support was 44.2 percent for Bush, 47.2 percent for Kerry, and 1.0 percent for Nader. Michigan also looks solid for Kerry.Bottom line: George Bush’s situation in all four of these key battleground states is dire. His support is well below 50 percent in all of them and he is currently trailing John Kerry in 3 of the 4. A clean sweep of all four states by John Kerry is a distinct possibility.

Posted by rteixeira on November 1, 2004 12:40 PM | Permalink

Conclusion: McCain is not in bad shape. I just got done reviewing the accuracy of polls taken immediately before the election in 2000 and I found similar discrepancies. That case is not an analogous one, however, as those who were old enough to vote then may remember. Al Gore set off his media-bomb on the Friday before the election: the revelation that his campaign had been sitting on for months that Bush had a DUI arrest back in the 1970’s which had not been disclosed. This revelation significantly drove down Bush’s poll numbers. We need to be ready for the Dem’s media-bombs this time around. They seem to focus on personal/character issues. Especially those with a sex-scandal tinge (Mark Foley/Ted Haggard).

So be vigilant. Donate $20-$200 to McCain/Palin today. We need to keep BHO and the other jerk from taking over the country.