SJ wrote:
For a demographic breakdown of visitors to the site in
the US, the
Hitwise data are pretty good. Here are data from early March:
http://hcs.harvard.edu/%7Esjklein/WP-Charts-030206.doc
With the caveat that their breakdown by age starts at 18, which
obviously omits a sizable chunk of the online population, and we can be
fairly confident that this affects Wikipedia more than some other sites.
How much this matters may depend on what lines of research you're
interested in pursuing.
--Michael Snow