***** To join INSNA, visit http://www.insna.org ***** The software ORA (Organizational Risk Analyzer) available at www.casos.cs.cmu.edu has a Silo Index in the Subgroups Report. The index is applied to the subgroup rather than the network as a whole. This corrects your concern about two groups merging into one. The index spans from 1 (all in-group ties, no out-group ties) to -1 (all out-group ties, no in-group ties). Ian McCulloh On Thu, Aug 29, 2013 at 9:04 PM, Justin Koonin <[log in to unmask]> wrote: > ***** To join INSNA, visit http://www.insna.org ***** > Hi everyone, > > I'm fairly new at SNA research and have a question about a possible index > of collaboration between groups. > > I have a graph whose nodes represent individuals in an organisation, > and whose edge values represent some measure of collaboration between each > pair of individuals > > The individuals are grouped into different units. I would like to measure > the extent of collaboration between different units. > > My sense is to define a "collaboration index" = > > (Sum of weights of edges between different units)/ > (Total sum of weights of all edges) > > Thus, if an organisation exists in silos (I.e no co-operation at all > between members of different units) the collaboration index would be 0. On > the other hand, if membership of a particular unit played no role at all in > determining whom an individual works with, the collaboration index would be > very close to 1. > This measure tends to favour many smaller units over a few larger ones, so > possibly a better measure is > > (Sum of weights of edges between different units)/ x (Number of pairs of > individuals)/ > (Total sum of weights of all > edges) (Number of pairs of individuals in > different units) > > However neither of these measures is robust to changes in the structure of > the units themselves. For example, if two units are working closely > together and decide to amalagamate into one bigger unit, the collaboration > index would go down, which seems counterintuitive. > > So I'd like to know if there are other, better, ways to measure this sort > of thing? > > Thanks in advance... > _____________________________________________________________________ > SOCNET is a service of INSNA, the professional association for social > network researchers (http://www.insna.org). To unsubscribe, send an email > message to [log in to unmask] containing the line UNSUBSCRIBE SOCNET > in the body of the message. _____________________________________________________________________ SOCNET is a service of INSNA, the professional association for social network researchers (http://www.insna.org). To unsubscribe, send an email message to [log in to unmask] containing the line UNSUBSCRIBE SOCNET in the body of the message.