Hi,

> The best reference group I can think of would be Wikipedia users. Ideally,
> the best and cleanest way to get that sample is to publish the link on
> Wikipedia itself (e.g. on every 10'000th page or so). Do you see any chance
> to make that happen?

Please explain what you mean.  Every 10,000th user page?  A link to
the entire survey?   How would the link being on a page distinguish
contributors from non-contributors?

my idea was to display the link on every 10'000th article, not user pages, because ordinary users probably don't look much on user pages or discussion pages. The inviting text should make it clear that we are primarily conducting a survey of Wikipedia users (as opposed to contributors). This was just an idea, though...

If you're looking for a way to split visitors into two identical
groups, you could separate out anon IPs (mainly readers, not
contributors) that end in odd numbers from those that end in even
numbers...

Yes, displaying the link only to anon IPs seems a very good idea.

Best wishes,

Joachim

--
Joachim Schroer, Dipl.-Psych.
University of Wuerzburg
Department of Psychology II, Industrial and Organizational Psychology
Roentgenring 10
97070 Wuerzburg
Germany

Phone: +49 931 31 6062
Fax: +49 931 31 6063
http://www.psychologie.uni-wuerzburg.de/ao/staff/schroer.php
schroer@psychologie.uni-wuerzurg.de