But, of course, this kind of collaboration doesn't itself imply the absence of expertise. Experts can, after all, collaborate together. And Wikipedia certainly benefits from academics with specialized knowledge developing and patrolling articles they care about. (This is particularly true when measured in terms of Wikipedia's breadth -- it's hard to imagine many of the extremely technical scientific articles existing at all without the input of scientists who made it their business to fill out the encyclopedia's periphery.)

So "experts" in the traditional sense (e.g. academic pedigrees) do still matter in this collaborative environment. But a new study from researchers at Stanford University and Yahoo Research points to a complementary phenomenon: The definition of what makes someone an expert is changing. They search for expertise in Wikipedia's pages, and they find it, but what they're looking for -- what they call expertise -- uses different signals to project itself. Expertise, to these researchers, isn't who a writer is but what a writer knows, as measured by what they read online.

They write (pdf):

"We define an editor e's interest in a Wikipedia article a as the mean similarity between e's search queries and a ... Then we define e's expertise in a as the ratio of e's interest in a to the average editor's interest in a. Intuitively, someone is an expert in a topic if their interest is significantly above average." (bold added)

This may be "intuitive" to those immersed in Wikipedia's pages, structure, and data, but it's a new and radically distilled understanding of expertise: An expert is someone who knows something.

By this measure they do find Wikipedia's editors to be an expert bunch, with edits being made by people who have read more online in related fields than the average editor (their data comes from people who have allowed for tracking in Yahoo's toolbar). Their data also showed that people with greater "expertise" make the more significant Wikipedia edits -- "a good sign" they say, as "we would hope [such edits] would come from real experts." (bold again added)

The rest of their study fills out the picture of Wikipedia's editors a bit, based on browsing history. Editors "search more, read more news, play more games, and, perhaps surprisingly, are more immersed in pop culture," spending more time on sites such as YouTube. They also frequent porn and social-networking sites less frequently than the average web user, as a percent of places they visit. They visit three times as many web pages than Wikipedia readers who are not editors, and nine times as many as those who don't read Wikipedia at all. Overall, the authors write, Wikipedia's editors are "more sophisticated than usual Web users."

Wikipedia, despite its faults, is a special place, one where this new definition of "expert" is conceivable and can exist alongside more traditional notions. This seems less the case outside of Wikipedia's sprawling lands, where expertise is as fraught as ever, and web clicks alone don't buy you much in the way of respect.