One of the most common refrains you hear as a reporter is that the reason a particular politician is doing well is because the media is giving him/her a pass.

US President Barack Obama speaks during a press conference in the Brady Press Briefing Room of the White House in Washington, DC, March 6, 2012. SAUL LOEB/AFP/Getty Images

The problem with that free pass theory? The data just doesn’t bear it out, at least according to a new Pew Research Center study that analyzed the “tone and volume of candidate coverage during the 2012 primary seasons from January 2 - April 15”.

In the 15 weeks in which Pew conducted its analysis, President Obama’s negative coverage outweighed his positive coverage in every single one of them — the only candidate Pew studied where that was true.

“While a sitting president may have access to the ‘bully pulpit’ that does not mean he has control of the media narrative, particularly during the other party’s primary season,” concluded Pew’s Tom Rosenstiel in a memo detailing the findings. (There is a ton of fascinating stuff in the study; you can read it in full here.)

Here’s a chart that tells that story:

In no week did the amount of positive press coverage of Obama go above 25 percent and for the entire 15 weeks it averaged 18 percent positive as compared to 48 percent neutral and 34 percent negative.

Compare those numbers to Romney’s positive/negative press coverage in the Pew data. In those same 15 weeks, positive coverage of Romney outweighed negative coverage in six of them while four more weeks were roughly a draw between positive and negative coverage. (That means there were five weeks where Romney’s negative coverage outdistanced his positive coverage. Math!)

Overall, 39 percent of Romney’s press coverage was positive as compared to 29 percent which was neutral and 32 percent that was negative.

There are, of course, mitigating factors to these numbers. The Republican primary, naturally, dominated the media’s attention during this 15-week period and virtually every word out of the GOP field’s collective mouth was negative about President Obama. The resulting coverage, which detailed those claims, therefore, was negative.

And, as Rosenstiel¿ points out, much of the Obama coverage also mentioned the still-lagging economy — making it more likely to tip into the negative territory.

Those caveats aside, it’s still striking that for all the chatter about Obama’s preferential treatment by the media, the data tells a very different story. And the data doesn’t lie.