Compare methods

	E-I Index	Dyadic Analysis	Isolation Index
Field	Sociology	Sociology	Sociology
Family	Process / pipeline	Regression model	Process / pipeline
Year of origin	1988	1981	1954
Originator	David Krackhardt & Robert Stern	Holland & Leinhardt (p1); Kenny (Social Relations Model)	Wendell Bell (formalization of P* indices)
Type	Index of the relative balance of between-group versus within-group ties	Analysis of the dyad as the unit, decomposing relational effects	Exposure-dimension segregation index
Seminal source	Krackhardt, D., & Stern, R. N. (1988). Informal networks and organizational crises: An experimental simulation. Social Psychology Quarterly, 51(2), 123–140.	Holland, P. W., & Leinhardt, S. (1981). An exponential family of probability distributions for directed graphs. Journal of the American Statistical Association, 76(373), 33–50.	Bell, W. (1954). A probability model for the measurement of ecological segregation. Social Forces, 32(4), 357–364.
Aliases	EI index, external-internal index, Krackhardt-Stern E-I ratio, E/I ratio	dyad analysis, dyadic data analysis, social relations model, dyad census	P* isolation index, interaction index, exposure index, Bell isolation index
Related	5	4	5
Summary	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.	Dyadic analysis treats the dyad — the pair of actors and the relation between them — as the unit of analysis, separating the relational outcome into what each actor brings to all their relationships and what is unique to the specific pair. It spans the descriptive dyad census of network analysis and statistical frameworks such as Holland and Leinhardt's p1 model and Kenny's Social Relations Model, all of which respect the structural non-independence inherent in relational data.	The isolation index measures the exposure dimension of segregation: the extent to which members of a minority group are exposed only to one another rather than to members of other groups. It answers the question 'what is the own-group share of the typical neighbor (or classmate, or coworker) that a member of the focal group encounters?' Unlike evenness measures, it depends on the relative size of the group as well as its spatial distribution.