***** To join INSNA, visit http://www.insna.org ***** Daniele, I can offer one approach to this question: When you say normalize tie strength and ask the question "under what condition is a tie weak or strong", you are making an implicit comparison to a null model. For example, you could normalize the w(A,B) tie by W(A,B)_normalized = w(A,B)/(W_A * W_B) where W_A=sum_j[w(A,j)] and W_B=sum_j[w(j,B)] are the respective total activities of the nodes A,B and are generalizations of degree; you would be comparing the strength of that tie to its expected strength in a randomized network in which the activities of each node are preserved. Here "activity" could be directed or undirected (as per your example: jetsetters=high activity; homebodies=low activity). So if your question is really "How do I choose an appropriate null model to gauge the significance of ties", then I would say it depends on which features of the network you deem significant. (For example, in a randomized model with generalized degree preserved, the clustering/transitivity would not be preserved). Thus, if you disclude a feature from your null model you would be marginalizing ties between individuals that might be exceptional insomuch as they occur despite the statistical tendency to the contrary. Dylan Walker NYU, Stern -----Original Message----- From: Social Networks Discussion Forum [mailto:[log in to unmask]] On Behalf Of Daniele Quercia Sent: Thursday, June 11, 2009 1:33 PM To: [log in to unmask] Subject: [SOCNET] normalizing tie strength ***** To join INSNA, visit http://www.insna.org ***** Is there any way of normalizing tie strength in the literature? If one defines tie strength between A and B as the number of times A and B have seen each other, then tie strengths (for the whole social network) are not comparable. To see why, consider that A and B have met four times. Those four times entail completely different meanings in different situations - for instance, they would reflect either an absent tie (if A and B are jet setters and go out a lot) or a strong tie (if they are homebodies and rarely go out). Also, if one normalizes the strength on A->B based on A's total number of encounters, then one should choose a threshold that differentiates strong ties from weak ties, and this begs the question of how to choose that threshold :-) Daniele. http://www.cs.ucl.ac.uk/staff/d.quercia/ group blog: http://mobblog.cs.ucl.ac.uk/ (join us!) _____________________________________________________________________ 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.