The Democratic and Republican conventions boil down to a clash over Ronald Reagan's classic metric: "Are you better off than you were four years ago?" The Romney campaign, in its latest attempt to convince Americans the answer is a resounding "no," is pointing out that the U.S. has fewer jobs now than it did the day President Obama took office, meaning, according to Romney spokeswoman Andrea Saul, that Obama "hasn't created one single net new job since he's been president." Predictably, Democrats are offering up their own calculations, with speaker after speaker at the Democratic convention crediting Obama with creating millions of jobs since the recession he inherited bottomed out a year after he took office. Which is it — is Obama a failure at putting people to work, or a job-creating machine?

It's simple math — Obama hasn't added a single job: Democrats are using "a dizzying display of political hocus pocus," says Brady Cremeens at The Right Sphere, to make Americans think Obama's a wizard at creating jobs, and we're better off thanks to him. It's "a lie." Yes, some jobs have been created under Obama, but more have been lost. "Liberals are purposefully ignoring the net loss, which is the measurement that matters and tells the true story."

"The battle of better-offs"

The GOP numbers are true, but misleading: Yes, the U.S. had 133,561,000 non-farm jobs in January 2009, the month Obama took office, says Brian Beutler at Talking Points Memo, and roughly 200,000 fewer in July 2012. But, in early 2009, "the economy was shedding jobs at a terrifying clip." Within two weeks of Obama's inauguration, the number "had dropped precipitously to 132,837,000," so, even if you blame Obama for the bleeding he inherited, he has presided over a net jobs gain.

"The truth behind the GOP claim that Obama hasn't created a single net job"

The reality is that Obama's policies have worked: Mitt Romney is promising to strengthen the economy if he wins, says Steve Benen at MSNBC, but even he concedes that any president should be given six months to a year to get his economic team and policies in place. Measuring from the end of Obama's first year — Romney's own standard — Obama has added 4.5 million private sector jobs. Regardless, the GOP's argument has "a shelf life," as Obama should be in positive "net" territory by election day no matter when you start counting.

"The misguided argument over 'net' jobs"

Both sides are spinning this: "It's true that the president came into office at a time when the economy was cratering," says Doug Mataconis at Outside the Beltway, so it really is unfair to stick him for job losses in his first month. Remember, though, that Obama's stimulus passed on Feb. 17, 2009, and the administration promised quick results from that $800 million investment. If Obama accepts responsibility from there, he hasn't presided over a net job loss, but the tiny improvement is nothing to brag about.

"About those 4.5 million new jobs, Mr. President"

Read more political coverage at The Week's 2012 Election Center.