E-I Index
The external-internal (E-I) index, introduced by Krackhardt and Stern, measures the extent to which the ties of a group point outward to other groups versus inward to its own members. It is the number of between-group (external) ties minus the number of within-group (internal) ties, divided by the total number of ties. Ranging from −1 (all ties internal, perfect insularity) to +1 (all ties external), it is a compact summary of homophily and group closure that can be computed for a whole network, for each group, or for each node.
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Sources
- Krackhardt, D., & Stern, R. N. (1988). Informal networks and organizational crises: An experimental simulation. Social Psychology Quarterly, 51(2), 123–140. DOI: 10.2307/2786835 ↗
- Everett, M. G., & Borgatti, S. P. (2012). Categorical attribute based centrality: E-I and G-F centrality. Social Networks, 34(4), 562–569. DOI: 10.1016/j.socnet.2012.06.002 ↗
How to cite this page
ScholarGate. (2026, June 22). Krackhardt-Stern External-Internal (E-I) Index. ScholarGate. https://scholargate.app/en/sociology/e-i-index
Which method?
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- Homophily AnalysisSociology↔ compare
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- Social Network AnalysisNetwork analysis↔ compare