Two new polls give President Obama a slight lead over Mitt Romney in North Carolina, whether the country is better off than it was four years ago depends on how you phrase it, and some national polls show big discrepancies. Here's our guide to today's polls and why they matter.

Findings: Two polls give Obama a lead in North Carolina. Purple Strategies puts Obama ahead by 48 percent to Romney's 46 percent. High Point University/ Fox 8 showed Obama's ahead 48 percent to Romney's 44 percent.
Pollster: Purple Strategies, HPU/ Fox 8
Methodology: For Purple: Automated and online poll of 600 likely voters in North Carolina with a margin of error of +/-4 percentage points. For HPU/Fox 8: Telephone poll with 448 registered voters September 8 through 15 with a margin of error of +/-4.7 percent.
Why it matters: North Carolina "was the second-closest state" in 2008 according to Nate Silver, and the president's polling has not been as consistent in this state. In fact, it's the only swing state where Romney's consistently polled ahead of Obama. That said, in August, Silver remarked: "North Carolina just isn't that important to the electoral math" because other states are more likely to be the tipping point that swings the election one way or the other.
Caveat: The Real Clear Politics average still has Romney up by 1.8 in the state. Plus, these polls are looking at different samples — likely and registered voters.

Findings: People are more likely to think the country is better off than it was four years ago than they are to think they're personally better off. When asked if they are better off, 34 percent of likely voters say they're worse off, 31 percent say they're better off, and 34 percent say they're the same. However, when asked if the country is better off because Obama won, 48 percent say yes and 41 percent say no.
Pollster: Allstate/National Journal Heartland Monitor Poll conducted by FTI Communications.
Methodology: Telephone poll of 1,055 likely voters September 15 through 19 with a margin of error of +/-3 percentage points.
Why it matters: At the Washington Post's Ezra Klein today explains that this is "The poll result that explains the election."  Klein writes: "The conventional wisdom: Voters don't do counterfactuals. 'It could have been worse' is a losing message. That's been the Romney campaign's theory of the case, certainly, and many in the media have bought it. But perhaps we're not giving voters enough credit." By essentially asking if Obama did a good enough job, we find that voters say yes.
Caveat: It's all a matter of semantics isn't it?

Findings: National Journal finds Obama up by 7 points among likely voters, while two tracking poll paint a different picture. Gallup shows a tie; Rasmussen shows Obama up by one.
Pollster: Allstate/National Journal Heartland Monitor Poll conducted by FTI Communications, Gallup, Rasmussen
Methodology: For Allstate: See above. For Gallup: Seven-day rolling average of telephone interviews with 3,050 registered voters with a margin of error of +/-2 percentage points. For Rasmussen: Three day rolling average of 500 likely voters per night with a margin of error of +/-3 percentage points.
Why it matters: These three surveys reflect the confusing nature of polls this week. The tracking polls are the only ones showing a close race, and The New Republic's Nate Cohn frames it as "Gallup and Rasmussen v. World."  There are a number of reasons why Rasmussen might be showing a close race, Cohn writes. As for Gallup, it's less clear --"A similar situation unfolded in early August and ultimately the other polls moved into line with Gallup, not the other way around... Gallup is a credible strike against the view that Obama's bounce is persisting, but they look more like an outlier than a leading indicator of a tightening race." The New York Times's Nate Silver writes that Gallup is the "most powerful argument that Mr. Obama’s convention bounce is fading." On the other hand, Silver explains that last week Obama looked stronger in national polls than state ones, but this week, that's reversed. "That might lend credibility to the hypothesis that the some of the national trackers initially exaggerated the extent of Mr. Obama’s bounce — but also, that the Gallup poll now exaggerates his decline." Ronald Brownstein explains that National Journal's poll has been in line with "most other national surveys," and he adds that the best news for Republicans is that Obama has not been able to get his support above 50 percent. 
Caveat: These polls vary widely in methodology and samples, plus Rasmussen has a Republican lean.