Does anonymity give rise to hostility?

That's actually a pretty direct way to test it out, and it makes a lot of sense. Just make sure we test the pilot group against some kind of control group (I think that's what you meant). We can probably understand a lot about their experience from watching their activity at different types of pages (article space, talk space, project space), and particularly pay attention to their involvement in Wikiquette Alerts and what not.

Randomran17:53, 29 December 2009