The exercise revealed numerous errors in both encyclopaedias, but among 42 entries tested, the difference in accuracy was not particularly great: the average science entry in Wikipedia contained around four inaccuracies; Britannica, about three.
In the study, entries were chosen from the websites of Wikipedia and Encyclopaedia Britannica on a broad range of scientific disciplines and sent to a relevant expert for peer review. Each reviewer examined the entry on a single subject from the two encyclopaedias; they were not told which article came from which encyclopaedia. A total of 42 usable reviews were returned out of 50 sent out, and were then examined by Nature's news team.
Only eight serious errors, such as misinterpretations of important concepts, were detected in the pairs of articles reviewed, four from each encyclopaedia. But reviewers also found many factual errors, omissions or misleading statements: 162 and 123 in Wikipedia and Britannica, respectively.
The biggest weakness in Wikipedia appears to be its structure.
Nature said its reviewers found that Wikipedia entries were often poorly structured and confused.
"But it is not the case that errors creep in on an occasional basis or that a couple of articles are poorly written," Tom Panelas, director of [Encyclopedia Britannica] corporate communications is quoted as saying in Nature.
"There are lots of articles in that condition. They need a good editor."
Meanwhile, nature claims the articles it chose were "on subjects that represented a broad range of scientific disciplines," (Nature.com), but I beg to differ. If you look at the list, there's a lot more from biology than all the physical sciences combined, and there are mere token entries for math (Wolfram, Pythagoras’ theorem) and engineering/technology (field effect transistor), and I don't see any for the social sciences (though one can debate whether there should have been). Also interestingly, despite my background being strongly NOT biology, I know more about the biology things listed (Cambrian explosion, Punctuated equilibrium) than a number of those physics things they DO bother to mention (cavity magnetron). Who picked these articles anyway? There is a single astronomy article listed (Chandrasekhar) FYI, though one could again argue that it's astrophysics, a branch of physics.
And amusingly, the Wikipedia ones that Nature found errors in have little tag marks at the top. :)