A lot of governors want to be the next president, and already they're starting to make a similar case: Vote for me. I created jobs.

Already last week, Jeb Bush's new Super PAC, Right to Rise, bragged that Bush's "limited government approach helped unleash one of the most robust and dynamic economies in the nation, creating 1.4 million net new jobs" in Florida while he was governor.

Texas Gov. Rick Perry is likewise mulling another campaign. If he does run, you can expect him to once again run on his economic record, as he did in 2012.

Of course, Governors Mike Pence, Mitt Romney, Chris Christie, and Democrat Martin O'Malley could all use the same argument if they get in, too.

And while the narrative of job growth on their watch might get voters' attention, a close look at the numbers reveals more nuance than what these candidates might give in a stump speech. No surprise there.

Here at Vox, we ran the numbers, tallying up job growth in states during the time period a likely 2016 candidate was in the governor's mansion. The result: all of the candidates have positive numbers they can use. From Texas to New Jersey to Wisconsin, employment did in fact grow. But then, during much of the time these governors were in office, there was job growth nationwide. And if much broader economic forces were at work, that raises the question of just how much credit these candidates can take.

Here's a rundown of what happened in key Republican states and an assessment of just how much they can take credit:

The basic numbers

We tallied up total job growth for the governors who are getting the most buzz in the 2016 race. The below chart shows the total percent change in a state's employment level versus the percent change in the national figure during a given governor's term. What it shows is that within the broad field of candidates is a wide range of economic success stories:

Of course, Rick Perry has been governor for 14 years, whereas Mike Pence has only been Indiana's governor for two years. So let's look at ratios of job growth rates. The below chart shows the ratio of job growth in any given candidate's state to that in the country as a whole.

One thing this allows you to do is make a rough divide between governors who outdid the rest of the nation and those who didn't. Anyone with a ratio greater than 1, then, did better than the US as a whole, while less than 1 means worse. This means Christie, O'Malley, and Romney don't have the hottest numbers to tout. Meanwhile, Bush, Jindal, and Perry perhaps have the strongest cases for themselves — Perry in particular had job growth four times the national rate. Since Perry took office in December 2000, for example, Texas has added 2.2 million new nonfarm employees to its rolls, growth of more than 23 percent. Both of those figures are impressive, but is he really directly responsible for creating those jobs?

"Accidental" job growth

Already a potential 2016 candidate, Sen. Ted Cruz of Texas, has raised the question. At a May 2014 press conference, Cruz took aim at Texas Gov. Rick Perry and politicians taking credit for their state economies more broadly.

"There isn't a politician in this country who's responsible for the economic growth we have," Cruz said, as reported by the Dallas Morning News. "The economic growth has come from the private sector, it's come from entrepreneurs. Nothing drives me crazier than politicians who run around talking about the jobs they've created."

This may well be one dividing line in the 2016 campaign field: that between governors claiming credit for state job growth and national-level legislators, like Cruz, poking holes in that story.

And Cruz does have a point: governors may preside over great economic growth, but they're rarely responsible for it...at least, not the lion's share of it.

"Governors and state legislatures often give themselves huge credit for accomplishments that are in fact more accidental," says Gary Burtless, a senior fellow in economic studies at the Brookings Institution. For example, he adds, "The governor of Texas looks great in years that the price of oil is high or rising."

So when oil prices were booming up until these last few months of Perry's term in office, he has looked really great on "job creation." Likewise, during Bush's tenure in Florida from 1999 to 2007, the state population grew by nearly 17 percent, compared to the national level of 8 percent. That kind of population growth fuels growth in construction, as more homes and office buildings are needed. That undoubtedly contributed to economic growth. (And Bush left office right before the housing bubble popped, crippling the Florida economy even more than much of the rest of the nation.)

This brings up another important point, Burtless adds: "For the economy as a whole, there are ups and downs. And I think the gyrations up and down are even bigger at the state level than the national level, and that's because states tend to specialize in something."

So Texas, for example, will reflect the fortunes of the oil industry far more than the finance industry. Ohio will be more manufacturing-dependent than any other state. And that means Perry and Kasich will have different stories to tell, even though Perry has nothing to do with the price of oil and Kasich can't help that manufacturing employment is only slowly creeping back.

Bigger forces than any state

A governor can do things to encourage a state's economy, of course. Having lower taxes or a better education system than the state next door might lure in some residents or businesses. Making smart budget decisions likewise will boost a state's credit rating, which in turn makes it easier for the state to finance the things it wants to spend on.

"Governors clearly have an impact on budget and tax policy matters, and they also influence the economic development strategy for their states," says S&P analyst Robin Prunty. But she, too, emphasizes the huge factors outside a governor's control: "There are other issues outside of a policymaker's influence, such as the individual state economic profile and macroeconomic conditions, which will also influence economic growth and development."

Indeed, a state's economy is subject to not only the whims of markets like housing and oil, but the national-level economy and policies.

In the last few years, states have benefited from a slowly strengthening recovery and national-level polices connected to that recovery. Jindal and Perry, both in office when Congress enacted President Obama's stimulus bill in 2009, likely benefited from that infusion of spending and jobs. Likewise, the Fed's extraordinary measures during and after the financial crisis helped stabilize the nation and have also eased lending, making borrowing and homebuying easier.

Jeb Bush may be the first governor to tout his state's economic record on the 2016 campaign trail, but he's not the last. And as these sorts of statements multiply along with the field of candidates, it's always a good idea to treat these claims with skepticism.