What is a research-supported ratio for lurkers to posters in online
communities?    People commonly say 10:1, but I haven't seen any data
to back that number up.   It would also be helpful to know if that
ratio changes between "generic" communities and topic-based ones (i.e.
a community mailing list versus a hobbyist website).

Hi calvarez,

Measuring lurkers to posters is not an easy task.

I found an article that agrees a 10:1 lurker:poster ratio is typical
(http://www.sfgate.com/~tex/innkeeping  -- scroll down to Posting and
Lurking), but as you say, there isn't much data to back it up.

Looking towards the academic institutions, we start to find a few
theses (that's thesis, plural), that delve into the subject.  Among
them is one from University of Guelph in Ontario, Canada by Robert
Blair Nonnecke (http://snowhite.cis.uoguelph.ca/~nonnecke/research/blairsthesis.pdf)
who researched this very topic (or very similar to it): _Lurking in
E-mail-Based Discussion Groups_.  Page 72 of the PDF has some of his
results from a 3 month study of 147,000 messages in 109 discussion
lists. Among the results:
Average lurker:poster ratio: 55%
lurking ratio (LR) in health groups: 45%
LR in software groups: 82%

In addition, in the appendix of his thesis, are a couple conference
papers that he presented.

As you can see, Blair found that the LR is really closer to 1:1, not
the previously thought 10:1 (though he does reference a 90% value in
one of his conference papers)

I invite you to take a look at this thesis for some very in-depth data
and analysis of the lurker's mind.

Google search used to find information:
lurker to poster ratio online communities data

(adding data was key to this search)

Hope this helps answer your question

Thanks for using GoogleAnswers