This chapter analyzes why computers and telecommunications have not created computcr-mediated work environments for collaboration that are as successful as physically shared environments. Our goals are, first, to identify the mechanisms by which proxin~ity makes cnl-laboration easier, concentrating on the way it facilitates interpersollal interaction and aware-ness; and second, to evaluate how current computer-mediated communication technologies provide or fail to provide the key benefits of proximity. We use a decompositional frame-work that examines how visibility, copresence, mobility, cotemporalitv and other affordances of media affect the important collaborative tasks of initiating conversation, establishing common ground, and maintaining awareness of potentially relevant changcs in the collabo-rative environment. Increasingly, collaborating with other people is as likely to take place over distance or time as it is face-to-face. An abundance of new communication technologies has been dcvcloped to mediate remote collaboration: e-mail, bulletin boards, instant messaging, document sharing, videoconferencing, awareness services, and others. Yet collaboration at a distance remains substantially harder to accomplish than

this paper examines these relationships in more detail, and asks whether contributions, perceived benefits, and the relationships among them were different for owners of the lists (formal leaders), active posters, and lurkers of the groups, and for nonwork-related and work related groups. To test our hypotheses, we conducted repeated measures ANOVAs with respondent role (owner or other member) and group type (non-work or work-related) as fixed effects, and group size and content volume as covariates. Building 18 2 3 4 5 6 7 8 9 10 11 12 13 14 1 . T o t a l T i m e 1 . 0 0 2. Infrastructure Maintenance . 6 8 * * 1 . 0 0 3. Social Control .29** .28** 1.00 4. Social Encouragement .42** .29** .47** 1.00 5. External Promotion .31** .33** .29** .32** 1.00 6. Content Provision .87** .65** .29** .36** .28** 1.00 7. Audience Engagement .39** .11* .12* .16** .06 . 24** 1.00 9. Information Benefits .16** .05 -.10 .13* .00 .06 .15** .24** 1.00 10. Social Benefits .33** .17** .20** .35** .22** .28** .17** .30** .30** 1.00 11. Altruistic Benefits .28** .23** .10 .34** .15** .26** .13* .32** .28** .49** 1.00 12. Work-Related Group -.06 .07 -.09 .04 -.02 -.03 -.02 .28** .08 -.12* .09 1.00 13. Log (Group Size) -.01 -.11 -.02 .02 -.09 -.11* .10 .07 .20** -.08 -.05 .17** 1.00 14. Log (Message Volume + .01) .19** -.04 .08 .13* -.03 .08 .13* .06 .21** .08 .09 -.18** .52** 1.00 15. # of Members Known Outside the Group .14** .20** .06 .08 .07 .31** -.01 .06 -.06 .02 .12* .05 -.07 .01 Pairwise Ns range from 325 to 385 * p <= 0.05; ** p <= 0.01 Table 3: Correlations among measures 19 RESULTS A premise of this research is that community building requires significant expenditures of time and effort on the part of members. The descriptive analysis presented below shows that members reported inv...

Turnover in online communities is very high, with most people who initially post a message to an online community never contributing again. In this paper, we test whether the responses that newcomers receive to their first posts influence the extent to which they continue to participate. The data come from initial posts made by 2,777 newcomers to six public newsgroups. We coded the content and valence of the initial post and its first response, if it received one, to see if these factors influenced newcomers' likelihood of posting again. Approximately 61% of newcomers received a reply to their initial post, and those who got a reply were 12% more likely to post to the community again; their probability of posting again increased from 44% to 56%. They were more likely to receive a response if the y asked a question or wrote a longer post. Surprisingly, the quality of the response they received---its emotional tone and whether it answered a newcomer's question---did not influence the likelihood of the newcomer's posting again.

This article describes and validates an agent-based model that integrates social psychological theories on collective effort, group identity, and interpersonal bonds to understand trade-offs in designing online communities. The model is then used to examine when different types of moderation in online communities will be valuable: no moderation in which all members are exposed to all messages, community-level moderation in which off-topic messages are deleted for everyone in the group, and personalized moderation in which people see different messages based on their interests. Compared to a no-moderation control, personalized moderation is effective in increasing members ’ contribution and commitment, especially in topically broad communities and those with high message volume. In contrast, community-level moderation increases member commitment but not contribution. By removing off-topic messages, community-level moderation increases members ’ information benefits at the expense of their opportunities for developing online relationships. This research demonstrates the value of computational modeling to synthesize narrow theories to describe behaviors in a complex system and to inform online community design.

Communities of practice (COPs) play an important role in the use and transfer of knowledge within and between organizations. Increasingly, new technologies, such as electronic mail and the Web, are being applied to create alternative infrastructures for these communities. This paper presents a model of dynamic communities of practice (DYNACOP) that integrates the processes of member development, structural change, and communications costs. The DYNACOP model was calibrated and validated with empirical data from a sample of Internet listservs. The model predicts that infrastructures that reduce communication costs will ultimately result in slower development of focused, stable communities of practice. While reduced communication costs increases the efficiency of communication, it also alters the processes by which members form beliefs about the community, which in turn affects the structural development of a community’s membership. Hence networked communities of practice are expected to have larger and more diverse, but also less stable and focused, memberships than traditional face-to-face associations.

Group Evolution (ViSAGE), that views the organization of human communities and the experience of individuals in a community as contingent upon on the dynamic properties, or micro-laws, of social groups. The laboratory facilitates the theorization and validation of these properties through an iterative research processes that involves (1) forward simulation experiments, which are used to formalize dynamic group properties, (2) reverse engineering from real data on how the parameters are distributed among individual actors in the community, and (3) grounded research, such as participant observation, that follows specific activities of real actors in a community and determines if, or how well, the micro-laws describe the way choices are made in real world, local settings. In this article we report on the design of ViSAGE. We first give some background to the model. Next we detail each component. We then describe a set of simulation experiments that we used to further design and clarify ViSAGE as a tool for studying emergent properties/phenomena in social networks.

In this article, we advocate a new approach in theory development by translating and synthesizing insights from multiple social science theories in an agent-based model to understand challenges in building online communities. To demonstrate the utility of this approach, we use it to examine the effects of three types of discussion moderation in conversation-based communities: no moderation, in which all members are exposed to all messages, community-level moderation, in which off-topic messages are deleted for everyone in the group, and personalized moderation, in which people see different messages based on their interests. Our results suggest that personalized moderation outperforms the others in increasing members ’ contribution and commitment, especially in topically broad communities and those with high message volume. In comparison, community-level moderation increases commitment but not contribution. Our results also reveal a critical trade-off between informational and relational benefits. This research demonstrates the value of agent-based modeling in synthesizing more narrowly-focused theories to describe and prescribe behaviors in a complex system, to generate novel theoretical insights that were out of scope for the component theories, and to use these insights to inform the design of online communities.