UPDATE: After you read this story, make sure you check out the follow up piece. Editors at Embargo Watch have found evidence that The Sustainable Food Trust manipulated the media to prevent public criticism of this paper.

Yesterday, in an aside to a post criticizing an astroturf political campaign in California, Mark mentioned a new study that supposedly found GM corn causes tumors in rats. As Mark said in an update to that post, this study is severely flawed, but I wanted to follow-up on that with some discussion about why it's flawed.

After all, the study was peer-reviewed, right? Doesn't that mean we can trust it?

Here's the thing. Peer review is not perfect. It's not a panacea. It's simply the basic level of due diligence. By submitting work for peer review, a scientist has allowed people outside her own team to critique her work. And the journal might require some changes to the paper based on the critique — anything from edits for clarity to requesting that the scientist perform another experiment in a different way. If a paper hasn't gone through peer review, you should be more skeptical of it. Avoiding peer review means that the researcher decided to show the public her results before allowing those results to be critiqued by independent experts.

But, at the same time, just because something has gone through peer review doesn't mean it's been certified to be accurate. It just means that roughly three other experts have looked at the paper before publication. There's still a lot of room for things to go wrong. Peer review is like the bouncer at the door. The bouncer doesn't guarantee that every person in the bar would be a good person for you to date. Even if a paper gets through, you still have to think about it critically and evaluate it on its own merits. This recent paper on GM corn and rat tumors is an excellent example of that ...

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