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Re: Betweenness in digraphs & UCINET

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Thu, 8 Aug 2002 15:40:10 +0200

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 ```Dear Dorothea, I don't know which version of UCINET you used. I tried the BURT-Data in UCINET V and in an old DOS-Version distributed free on the analytic technologies homepage and both versions gave the correct result of 16 for the non-normalised betweenness. According to the UCINET manual the routine is based on Freeman (1979). The UCINET manual says: Let bjk be the proportion of all geodesics linking vertex j and vertex k which pass through vertex i. The betweenness of vertex i is the sum of all bjk where i, j and k are distinct and j < k. Betweenness is therefore a measure of the number of times a vertex occurs on a geodesic. The normalised betweenness centrality is the betweenness divided by the maximum possible betweenness expressed as a percentage. This procedure should only sum over every pair once, because of the jHi all, > >UCINET does calculate betweenness for asymmetric data, but I can't find >out which routine is used. Playing with a very simple graph, the advice >net of Burt (1982: 25), UCI yields betweenness scores of zero for all >actors, although actor 5 is the only go-between on 16 geodesics of >length 2 which are correctly identified. Is there a threshold of >connectedness for the calculation routine used? >The advice networks consists of 10 nodes which can be grouped to four >perfect blocks. 1 to 4 only have an outgoing tie to 5. Actor 6 is >unconnected. 5 has outgoing ties to 7 to 10. 7 to 10 are a perfect >clique. >Thank you for any help > >Dorothea > > >-- >Prof. Dr. Dorothea Jansen >Lehrstuhl für Soziologie der Organisation >Deutsche Hochschule für Verwaltungswissenschaften >Postfach 1409 >D-67324 Speyer > >Tel. 06232/654-364 oder -359 (Sekretariat) >Fax: 06232/654-418 oder -306 >Homepage: http://www.dhv-speyer.de/jansen/ > ----------------------------- Mark Trappmann [log in to unmask] http://www.fb1.uni-essen.de/trappmann Telefon ++49 (0)201-183-2586 (Uni Essen)              (0)203-663944 (Duisburg)```