Doctoral Dissertations

Date of Award

Spring 1999

Document Type


Degree Name

Doctor of Philosophy (PhD)

Degree Program

Information Systems


Tepper School of Business at Carnegie Mellon University


Graduate School of Industrial Administration

First Advisor

Kathleen Carley, Ph.D.

Second Advisor

Robert Kraut, Ph.D.


online communities, community dynamics, internet, computer mediated communication, social media

Subject Categories

Databases and Information Systems


It has been proposed that online social structures represent new forms of organizing which are fundamentally different from traditional social structures. However, while there is a growing body of empirical research that considers behavioral aspects of online activity, research on online social structure structural remains largely anecdotal. This work consists of three papers that combine previous studies of traditional social structures, empirical analysis of longitudinal data from a sample of Internet listservs, and computational modeling to examine the dynamics of social structure development in networked environments.

The first paper (Title: When is a Group not a Group: An Empirical Examination of Metaphors for Online Social Structure) empirically examines the appropriateness of metaphors which have been used in popular and academic discussions of online social structure. The structural features implied by the metaphors are compared with data from a random sample of e-mail based Internet listservs. The results indicate that the most commonly applied metaphor ('small group') does not accurately represent the membership and communication features observed in these online social structures. Furthermore, there is evidence that the characterization of online structures in these terms has significantly biased the selection of cases and stories in the current literature. The empirical results also suggest that the metaphor of' voluntary associations' is more accurate and hence is better foundation for theorizing about online social structure.

In the second paper (Title: Membership Size, Communication Activity, and Sustainability: The Internal Dynamics of Networked Social Structures) presents a resource-based theory of social structures. This model implies that structural features, such as size and communication activity, play both positive and negative roles in the sustainability of a social structure. Prior work has argued that networked communication technologies will significantly reduce the negative impact of size and communication activity, resulting in fundamentally different social structures. However, analysis of the longitudinal data from the e-mail based Internet listservs indicates that size and communication activity continue to have both positive and negative effects. This suggests that while the use of networked communication technologies may alter the form of communication, balancing the positive and negative impacts of membership size and communication activity remains a fundamental problem underlying the development of sustainable social structures.

The third paper (Title: Communication Cost, Attitude Change and Membership Maintenance: A Model of Technology and Social Structure Development) integrates processes of individual belief change and member movement in a dynamic model of online social structure development. Contributed messages create a composite signal, providing members with information about the benefits of membership. This information changes members' beliefs about the structure and affects their willingness to remain members. The processes of communication, individual belief change, and membership maintenance form a cycle that underlies the development of the collective. Communication costs, a feature of the communication infrastructure, affect a social structure's development by moderating the process of member belief change. A dynamic, multi-agent computational model of social structure development was implemented, calibrated, and validated using the listserv data. Analysis of the model implies that reduced communication costs, as are expected in networked environments, slow down the development process, resulting in online social structures which have more (and more diverse) members while being less stable than traditional face-to-face associations.



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