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	E-I Index	Blockmodeling	Homophily Analysis
Ämnesområde	Sociology	Sociology	Sociology
Familj	Process / pipeline	Process / pipeline	Process / pipeline
Ursprungsår	1988	1976	1954 (concept); 2001 (synthesis)
Upphovsperson	David Krackhardt & Robert Stern	Harrison White, Scott Boorman & Ronald Breiger	Lazarsfeld & Merton (concept); McPherson, Smith-Lovin & Cook (synthesis)
Typ	Index of the relative balance of between-group versus within-group ties	Network partitioning into positions and a reduced role structure	Measurement of similarity-based tie formation
Ursprungskälla	Krackhardt, D., & Stern, R. N. (1988). Informal networks and organizational crises: An experimental simulation. Social Psychology Quarterly, 51(2), 123–140.	White, H. C., Boorman, S. A., & Breiger, R. L. (1976). Social structure from multiple networks. I. Blockmodels of roles and positions. American Journal of Sociology, 81(4), 730–780.	McPherson, M., Smith-Lovin, L., & Cook, J. M. (2001). Birds of a feather: homophily in social networks. Annual Review of Sociology, 27, 415–444.
Alias	EI index, external-internal index, Krackhardt-Stern E-I ratio, E/I ratio	block modeling, blockmodel analysis, generalized blockmodeling, CONCOR	homophily measurement, assortative mixing analysis, birds-of-a-feather analysis, tie-similarity analysis
Närliggande	5	4	4
Sammanfattning	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.	Blockmodeling is a family of methods that simplify a social network by partitioning its actors into positions — groups of actors who are equivalent in their pattern of ties — and summarizing the relations between positions as a compact image, or reduced role structure. Introduced by Harrison White, Scott Boorman, and Ronald Breiger in 1976, it shifts attention from individuals to the structural roles they occupy.	Homophily analysis quantifies the tendency of similar individuals to form ties — the principle that 'birds of a feather flock together'. It compares the rate at which people connect with others who share an attribute (race, gender, age, education, attitudes) against what would be expected by chance, distinguishing the homophily that arises merely from group sizes from the genuine, behavior-driven preference for similar others.