Nov. 2: For Romney to Win, State Polls Must Be Statistically Biased
By NATE SILVER
President Obama is now better than a 4-in-5 favorite to win the Electoral College, according to the FiveThirtyEight forecast. His chances of winning it increased to 83.7 percent on Friday, his highest figure since the Denver debate and improved from 80.8 percent on Thursday.

Friday’s polling should make it easy to discern why Mr. Obama has the Electoral College advantage. There were 22 polls of swing states published Friday. Of these, Mr. Obama led in 19 polls, and two showed a tie. Mitt Romney led in just one of the surveys, a Mason-Dixon poll of Florida.

Although the fact that Mr. Obama held the lead in so many polls is partly coincidental — there weren’t any polls of North Carolina on Friday, for instance, which is Mr. Romney’s strongest battleground state — they nevertheless represent powerful evidence against the idea that the race is a “tossup.” A tossup race isn’t likely to produce 19 leads for one candidate and one for the other — any more than a fair coin is likely to come up heads 19 times and tails just once in 20 tosses. (The probability of a fair coin doing so is about 1 chance in 50,000.)

Instead, Mr. Romney will have to hope that the coin isn’t fair, and instead has been weighted to Mr. Obama’s advantage. Read more…
November 2, 2012, 3:59 PM466 Comments
Revisiting Our February Jobs Prediction
By NATE SILVER
Friday’s jobs report was a reasonably strong one, economically speaking. The economy added 171,000 jobs in October, according to the government’s survey of business establishments. In addition, estimates of jobs growth were revised upward for August and September.

The unemployment rate, which is calculated through a separate survey of households, ticked up to 7.9 percent. But this was because it was estimated that more workers, 578,000, entered the labor force in October, outweighing what it said were 410,000 people who found jobs.

Is the report good enough to have an impact on the waning days of the campaign? There is a dispute in the political science literature about whether voters react to underlying economic conditions, or rather, to the news media’s coverage of the economy.

If it’s the real-world conditions that count, the actual act of the government publishing the jobs figures is unimportant. People will already have observed local economic conditions and incorporated them into their decision of who they might vote for. Read more…
November 2, 2012, 11:50 AM1050 Comments
Nov. 1: The Simple Case for Saying Obama Is the Favorite
By NATE SILVER
If you are following some of the same people that I do on Twitter, you may have noticed some pushback about our contention that Barack Obama is a favorite (and certainly not a lock) to be re-elected. I haven’t come across too many analyses suggesting that Mitt Romney is the favorite. (There are exceptions.) But there are plenty of people who say that the race is a “tossup.”

What I find confounding about this is that the argument we’re making is exceedingly simple. Here it is:

Obama’s ahead in Ohio.
A somewhat-more-complicated version:

Mr. Obama is leading in the polls of Ohio and other states that would suffice for him to win 270 electoral votes, and by a margin that has historically translated into victory a fairly high percentage of the time.
The argument that Mr. Obama isn’t the favorite is the one that requires more finesse. If you take the polls at face value, then the popular vote might be a tossup, but the Electoral College favors Mr. Obama.

So you have to make some case for why the polls shouldn’t be taken at face value.

Some argue that the polls are systematically biased against Republicans. This might qualify as a simple argument had it been true on a consistent basis historically, but it hasn’t been: instead, there have been some years when the polls overestimated how well the Democrat would do, and about as many where the same was true for the Republican. I’m sympathetic to the notion that the polls could be biased, statistically speaking, meaning that they will all miss in the same direction. The FiveThirtyEight forecast explicitly accounts for the possibility that the polls are biased toward Mr. Obama — but it also accounts for the chance that the polls could be systematically biased against him.

Others argue that undecided voters tend to break against the incumbent, in this case Mr. Obama. But this has also not really been true in recent elections. In some states, also, Mr. Obama is at 50 percent of the vote in the polling average, or close to it, meaning that he wouldn’t need very many undecided voters to win.

A third argument is that Mr. Romney has the momentum in the polls: whether or not he would win an election today, the argument goes, he is on a favorable trajectory that will allow him to win on Tuesday.

This may be the worst of the arguments, in my view. It is contradicted by the evidence, simply put. Read more…
November 1, 2012, 7:53 PM357 Comments
In Nevada, Obama, Ryan and Signs of a New (Democratic-Leaning) Normal
By MICAH COHEN
We continue our Presidential Geography series, a one-by-one examination of each state’s political landscape and how it is changing. Here is Nevada, the Silver State. FiveThirtyEight spoke with Jon Ralston, a longtime political reporter in Nevada who runs his own political commentary site, RalstonReports.com, and hosts a public affairs program also called “Ralston Reports;” and David Damore, an associate professor of political science at University of Nevada, Las Vegas.

With less than a week until Election Day, Nevada’s six electoral votes remain pivotal. After three days of campaigning were canceled so he could oversee the federal response to Hurricane Sandy, President Obama returned to the trail Thursday, including a stop in North Las Vegas in the afternoon. That was about the same time that Representative Paul D. Ryan spoke in Reno, Nev.

Nevada should be one of the more promising battleground states for the campaign of Mitt Romney and Mr. Ryan. The state’s economy is in disrepair. Its unemployment rate, 11.8 percent, is the worst in the nation, and personal bankruptcies and foreclosures have ravaged the state.

In addition, although their effect can be overstated, Mormons make up 9 percent of Nevada’s population, tied for the third-largest share of members of the Church of Jesus Christ of Latter-day Saints. Mormon voters are expected to overwhelmingly support Mr. Romney, a Mormon himself.

Yet, just a single poll all year has found Mr. Romney leading Mr. Obama in Nevada. The race appears close, but polls show Mr. Obama retaining a consistent, if narrow, lead of 3.4 percentage points. And Nevada remains one of the more solid bricks in Mr. Obama’s Electoral College “firewall.”

How has Mr. Obama’s support in Nevada weathered the state’s struggling economy? Or, as Mr. Ralston put it, “How in the world is the president not getting crushed here?” Read more…
November 1, 2012, 10:16 AM1536 Comments
Oct. 31: Obama’s Electoral College ‘Firewall’ Holding in Polls
By NATE SILVER
On Oct. 11, this blog posed the question of whether President Obama’s “firewall” in battleground states was all that it was cracked up to be.

At that point, Mr. Obama still technically held the lead in the FiveThirtyEight forecast in enough states to give him 270 electoral votes. But Colorado, Florida and Virginia had turned red in our map, meaning that our forecast suggested that Mitt Romney had better-than-even odds of winning them. Iowa was just on the verge of doing so. And Mr. Obama’s lead was down to just a percentage point or so in Ohio, which would have collapsed his firewall at its foundation.

Theories that the decline in Mr. Obama’s polls that followed the first presidential debate in Denver would somehow skip the swing states were not looking good — as dubious as the idea that tornadoes “skip” houses.

Instead, at that point, Mr. Obama’s position in the FiveThirtyEight forecast had declined for seven consecutive days. If he stopped the bleeding there, he might still be the Electoral College favorite, albeit a narrow one. But it wasn’t clear where the bottom was.

It turned out, however, that the worst was almost over for him. Mr. Obama had one more terrible day in the polls, on Friday, Oct. 12, when Mr. Romney’s chances of winning the Electoral College rose to almost 40 percent in the forecast. But that was when Mr. Romney’s momentum stopped.

Since then, Mr. Obama’s standing has rebounded slightly. His position in the national polls has stabilized; although the national polls continue to tell a different story about the race than the state polls do; it can no longer be said that they have Mr. Obama behind. Read more…
October 31, 2012, 10:38 AM1147 Comments
Oct. 30: What State Polls Suggest About the National Popular Vote
By NATE SILVER
Mitt Romney and President Obama remain roughly tied