Breadth of Wikipedia coverage
A new article by Alexander Halavais and Derek Lackaff in the excellent Journal of Computer Mediated Communication examines the breadth of topics covered by Wikipedia. This graph from the paper shows the relative coverage of Wikipedia by topic versus books in print:

It’s interesting to see where the significant differences are. Wikipedia seems to have a lot of coverage of music, geography, history and science. It doesn’t do so well in social science, law and medicine, relative to books. I guess this reflects the underlying incentives to contribute to Wikipedia. People may be knowledgeable about geography or history because it’s their hobby or it interests them. I have not yet met anyone whose hobby is the law. And real lawyers probably have high opportunity costs of writing Wikipedia articles about law.
