algorithm for finding social embeddedness in nested cohesive subgroups is
applied to high school friendship networks (e.g., Fig 2; boundaries of
grades are approximate) and to interlocking corporate directorates. The
usefulness of the measures of cohesion and embeddedness are tested against
outcome variables of school attachment in the friendship study and
similarity in corporate donations to political parties in the corporate
interlock study. The cohesion variables outperform other network and
attribute variables in predicting the outcome variables using multiple
identical findings are replicated for school attachment measures and
friendship networks in 12 American high schools from the AddHealth Study
(http://www.cpc.unc.edu/addhealth/), Adolescent Risk and Vulnerability:
Concepts and Measurement. Baruch
Fischhoff, Elena O. Nightingale, Joah G. Iannotta, Editors, 2002, The
National Academy Press.
James Moody and Douglas R. White, Social Cohesion and Embeddedness: A
Hierarchical Conception of Social Groups. American Sociological Review 8(1)
account for the development of collaboration among organizations in the
field of biotechnology, four logics of attachment are identified and
tested: accumulative advantage, homophily, follow-the-trend, and multiconnectivity.
We map the network dynamics of the field over the period 1988-99 (Fig 3 à1999). Using
multiple novel methods, including analysis of network degree distributions,
network visualizations, and multi-probability models to estimate dyadic
attachments, we demonstrate how a preference for diversity and
multiconnectivity in choice of collaborative partnerships shapes network
evolution. Cohesion variables outperform scores of other independent
Collaborative strategies pursued by early commercial entrants are
supplanted by strategies influenced more by universities, research
institutes, venture capital, and small firms. As organizations increase
both the number of activities around which they collaborate and the
diversity of organizations with which they are linked, cohesive subnetworks
form that are characterized by multiple, independent pathways. These
structural components, in turn, condition the choices and opportunities
available to members of a field, thereby reinforcing an attachment logic
based on connection to partners that are diversely and differently linked.
The dual analysis of network and institutional evolution offers a
compelling explanation for the decentralized structure of this
Walter W. Powell, Douglas R. White, Kenneth W. Koput and Jason Owen-Smith. Network
Dynamics and Field Evolution: The Growth of Interorganizational
Collaboration in the Life Sciences, 1988-99.Submitted to: American Journal of Sociology.
2002 Ulla Johansen and Douglas R. White, Collaborative
Long-Term Ethnography And Longitudinal Social Analysis of a Nomadic Clan In
Southeastern Turkey, pp. 81-99, Chronicling Cultures: Long-Term Field
Research in Anthropology, eds. R. van Kemper and A. Royce. AltaMira.
Visiting patterns and network traversal through strong ties create
structures of encounter between potential mates and of morphogenesis of
social structure consolidated through marriage (Fig 6) and childbirth (Fig
5b). Middle Eastern societies with patrilineages often have nested segments
whose cohesion vary with kinship distance. Study of the Turkish nomads
shows that marriage frequency also decays with bilateral kinship distance
(Fig 7). The decay is a power-law not an exponential, which indicates
preferential attachment with closer relatives (Fig 8), a feature that is
typical of societies with preferences for marriage with blood kin.
Power-law distributions of preferential attachment in social
networks are an indicator of complex forms of self-organization, as seen
with the ability of conflict in segmented lineage systems to escalate to
higher levels of opposition.
Douglas R. White and Ulla Johansen.Network Analysis and Ethnographic Problems: Process Models of a
Turkish Nomad Clan. Lexington. In Press.