The Encyclopedia Britannica has stepped up its attacks on the journal Nature by taking out large ads in both the New York Times and the London Times this past week. The unusually public dispute began last year when Nature published a study showing that Britannica and Wikipedia had almost the same level of accuracy. Britannica was obviously not pleased with this conclusion, but made no objections until March, when it at last published a set of objections to the study. Not pleased with Nature's response, Britannica is now taking the controversy to the masses.

The ads call on Nature to issue a "full and public retraction of the article," and the Britannica editors give five major reasons why they believe the methodology of the study was deeply flawed.

You reviewed text that was not even from the Encyclopedia Britannica

You accused Britannica of "omissions," on the basis of reviews of arbitrarily chosen excerpts of Britannica articles, not the articles themselves

You rearranged and re-edited Britannica articles

You failed to distinguish minor inaccuracies from major errors

Your headline contradicted the body of your article

At the end, the editors of Britannica call on Nature to "renew its long-standing commitment to good scholarship and send us the complete, unabridged reviewer reports on which the study was based." They also suggest that a "complete retraction of the article is in order. Nature should make the retraction promptly, if not for Britannica's sake, then for the sake of Nature's reputation and in the interest of good science."

Britannica is certainly not holding anything back in this battle, which is understandable, as it goes to the very heart of their corporate mission (and profit margins). Their criticisms certainly do make the Nature study sound flawed. Britannica claims, for instance, that "several of the articles you sent to reviewers were not from the Britannica at all. In one case a reviewer criticized us for text that we simply cannot identify. We do know, however, that it was not ours." How could Nature make such egregious mistakes as these?

Nature's response is simple and direct—they are standing by their original results. In their view, it is Britannica that is simply mistaken.

"Another Britannica criticism concerns the fact that we provided material from other Britannica publications, such as the Britannica Book of the Year. This was deliberate: the aim of our story, as we made clear, was to compare the online material available from Britannica and Wikipedia. When users search Britannica online, they get results from several Britannica publications. They have no reason to think that any one is less reliable than the others. In the case of some year-book entries, Britannica itself asks readers to reference the articles as coming from 'Encyclopaedia Britannica Online'?-exactly the source we set out to compare. "Other objections are simply incorrect. The company has, for example, claimed that in one case we sent a reviewer material that did not come from any Britannica publication. When the company made this point to us in private we asked for details, but it provided none. Now Britannica has identified the review in question as being on ethanol. We have checked the original e-mail that we sent to the reviewer who looked at the Britannica article on ethanol, and it is clear to us that all the reviewer's comments refer to specific paragraphs from Britannica."

Nature's larger point is that, in the end, specific mistakes do not matter much anyway, since the study was conducted blind. Errors made by the reviewers would have tended to affect both Britannica and Wikipedia equally.

"Our reviewers may have made some mistakes--we have been open about our methodology and never claimed otherwise--but the entries they reviewed were blinded: they did not know which entry came from Wikipedia and which from Britannica. We see no reason to believe that any misidentifications of errors would adversely affect one publication more than the other. And of the 123 purported errors in question, Britannica takes issue with fewer than half."

Britannica's biggest gripe, though, has still not been addressed. They mention several times in their advertisements that Nature has been unwilling to turn over all of the documentation behind the study, and Nature's response does not indicate that they will do so.

The battle underscores the way in which projects such as Wikipedia can undermine established authorities and business models. Whether this is wholly a good thing remains to be seen, as Wikipedia's own founder has told users not to cite his online encyclopedia as a source due to concerns over its accuracy. Hopefully, the competition between the two models will serve to improve both.