James Joyner posts on the ubiquity of Virginia political scientist Larry Sabato in the mass media. Like Joyner, I think part of the explanation is media laziness (and part of it is Sabato’s self-promotion), and I expect research on media expert use in various subdomains would find similar patterns in other areas of media coverage.

That said, I think citations to experts within each subdomain are distributed according to a long tail function, suggesting that while Sabato seems dominant because of his frequent citation by media outlets (and our human cognitive bias that makes events that occur 1/4 to 1/20th of the time seem more frequent than they actually are), the “field” actually predominates over him.