When I make a substantive contribution to Wikipedia, I tend to edit "off-line" until I'm satisfied with the text, and then post it in a single chunk. While I am only a WikiGnome in any case, the typical Wikipedia metric of "edit counts" would underestimate the contribution made by people who edit in a similar fashion. My own simple Python script exhibits this problem. To get some sense of the substance of any given edit, one would have to go beyond screen-scraping and perform analysis on the Wikipedia database -- something beyond my desktop computer. Fortunately, Aaron Swartz purchased "some time on a computer cluster" and came up with the following novel result:
When you put it all together, the story become clear: an outsider makes one edit to add a chunk of information, then insiders make several edits tweaking and reformatting it. In addition, insiders rack up thousands of edits doing things like changing the name of a category across the entire site -- the kind of thing only insiders deeply care about. As a result, insiders account for the vast majority of the edits. But it's the outsiders who provide nearly all of the content.
I'm looking forward to seeing these findings replicated.