Fernando Martel Garcia points me to this news article by Ben Goldacre:
For anyone with medical training, mainstream media coverage of science can be an uncomfortable read. It is common to find correlational findings misrepresented as denoting causation, for example, or findings in animal studies confidently exaggerated to make claims about treatment for humans. But who is responsible for these misrepresentations?
In the linked paper (doi:10.1136/bmj.g7015) Sumner and colleagues found that much of the exaggeration in mainstream media coverage of health research—statements that went beyond findings in the academic paper—was already present in the press release sent out to journalists by the academic institution itself.
Sumner and colleagues identified all 462 press releases on health research from 20 leading UK universities over one year. They traced 668 associated news stories . . .
The story is pretty much as you’d predict: a lot of the exaggeration comes in the press release.
I remarked that this makes sense. I agree. Of course, this is just a start, as I’m sure a lot of academics would be happy to put their names on various exaggerated claims! See, for example, here, where the researchers in question were very active with the publicity, and in which they dramatically overstated the implications on individual-level behavior that could be drawn from their state-level analysis. The lead research in this case was just a law professor, but still, we’d like to see better.
As this example illustrates, the problem is not necessarily any sort of conscious exaggeration or hype: I assume that the researchers in question really believe that their claims are supported by their data. For that matter, I assume that disgraced primatologist Mark Hauser really believes his theories.
To put it another reason: be skeptical of press releases, not because they’re written by sleazy public relations people, but because they’re written by, or with the collaboration, of researchers who know enough to make a superficially convincing case but not enough to recognize the flaws in their reasoning.