I think some of the ideas in the chapter will be easier to follow if we think about there being two activities, A and B. Many of the distinctions in the chapter revolve around the impact of non-participation in A on participation in B.

To distinguish peripherality and marginality:

• peripheral; non-participation in A enables participation in B
• marginal: non-participation in A prevents participation in B

Demands of multi-membership: A is a practice of one community, B of another. To be allowed to participate in B, one has to not do A.

I just wanted to draw attention the parallels between "paradigmatic trajectory" and "group prototype" from the  Hogg reading last week. In both cases, they are idealized notions, not necessarily matching any individual, but things that many individuals may aspire to. They may be reified as individual people ("be like Mike"), but don't have to.

More messages --> shorter messages; more turnover of group membership

Shorter messages --> more likely to get a reply 

 Table 3 has the main empirical findings:

• Column a: more members --> more messages
• Column b: more member --> more topic variability
• Column c: more members --> more member gain in next time period
• Column d: more members, messages, topic variability --> more member gain next time period
• Column e: more members --> more member loss next time period
• Column e: more members, messages, topic variability --> more member loss next time period

Some of the effect of membership size on changes in membership is mediated by number of messages sent and topic variability. But there is an additional effect of membership size even controlling for those mediating factors.

As mentioned in class last time, we'll try using the chatbox while co-located tomorrow (March 6) during class.

If you don't have a laptop (with wireless), and can't borrow one from a
friend, please post a comment here asking if anyone has a spare. If you
have a spare you could lend to someone, please also post a comment here.

In my own research related to online communities, I have done four types of studies:

•  observational studies, doing statistical analysis of usage patterns

Khopkar, Tapan, Li, Xin, and Resnick, Paul. Self-Selection, Slipping, Salvaging, Slacking, and Stoning: the Impacts of Negative Feedback at eBay. To appear in Proceedings of ACM EC 05 Conference on Electronic Commerce. Vancouver, Canada. 2005.

Lampe, Cliff and Paul Resnick. Slash(dot) and Burn: Distributed Moderation in a Large Online Conversation Space. In Proceedings of ACM CHI 2004 Conference on Human Factors in Computing Systems, Vienna Austria. 2004.

Resnick, Paul and Richard Zeckhauser. Trust Among Strangers in Internet Transactions: Empirical Analysis of eBay's Reputation System. The Economics of the Internet and E-Commerce. Michael R. Baye, editor. Volume 11 of Advances in Applied Microeconomics. Amsterdam, Elsevier Science. 2002.

• Controlled experiments in field settings

None of the approaches to individual (or community) consent that I've seen seem to properly account for the cost of asking for consent. I'm referring here to the cost to the subject or community, not the cost to the individual. Especially in very public on-line sites, and especially those devoted to technical matters, I believe that a majority of participants would not be bothered by research (especially research reported in a way where individuals could not be identified) but would be bothered by inquiries about whether research is permitted. Lurking is fine; off-topic conversation is damaging to the community.

One shortcoming of the existing approach to ethics of research is that it only considers the individual as the unit of analysis, in terms of costs and benefits and in terms of consent.

But particularly for this paper's second method of conducting research, participant observation, the costs and benefits mostly accrue to the community as a whole, and it doesn't make sense to think of consent as an individual process. The community has to decide whether it wants to allow the researcher to participate as a member, using whatever formal or informal process it uses. Individual members can choose not to be in the community, or they can choose to not interact with the researcher-member, but they can't make individual choices to prevent the researcher from being a member.

Hi