On 4/11/07, Oleg Alexandrov mathbot@hemlock.knams.wikimedia.org wrote:
Bottom line: registered users make the vast majority of edits (and, as of 2005, the top 1400 make 73% of them) but it's IP editors (and small-time registered users) who contribute most of the content.
However, from my own experience of watching 800 articles daily, most anon edits are bad, and the time I spend now reverting vandalism could actually be used writing things. This is just a sample case of course.
Your sample is biased, so don't be surprised when the results don't match. The articles people watchlist tend to be more popular and well-established, so they attract more vandals. Try checking the edit histories of 800 randomly-selected articles.