***** To join INSNA, visit http://www.insna.org ***** Friedkin defined the unique in and out degree nodes as distinct points. -Tom Carl Nordlund wrote: > ***** To join INSNA, visit http://www.insna.org ***** > > Hi SocNetters, > > I have a question on a centrality index - don't know if I just > invented a new one, or whether I have reinvented an old wheel of > unknown quality... > > In my PhD thesis, I play around with intl trade flow matrices, i.e. > directional valued matrices with quite large value-spans between > different actors. While primarily looking at the role-structures > (conceptualized through regular equivalence), I am also interested in > looking at the relationship between different indices of "centrality" > and more mainstream (actor-based) attributes on economic well-being. > > As I am especially interested in the number of trading partners each > country has, both with regards to exports and imports, I have > experimented with a simple heuristic for counting the number of > significant trading partners for each country. However, I don't know > if this same procedure has been done before - and if so, what this > type of degree-style centrality index is called. > > How I calculate the number of partners an actor has: > First, I look at the "outflow profile", i.e. the row-vector for each > actor. Each outflow that is larger than 0.5 percent of the total > outflow is included in my count. I.e., if an actor has a total > outdegree of 1000, I count the number of outflows which are higher > than 5. Secondly, I do the same thing for the "inflow profile", i.e. > by looking at the col-vector for each actor. Similarly, I count all > inflows that are above 0.5 percent of the total inflows to the actor. > Then I calculate total number of partners by adding the number of > inbound and outbound partners. (The 0.5 percent "significance > threshold" is of course arbitrary). (As the same partner actor could > be counted twice - inbound as well as outbound - one could choose to > only count each trading partner once). > > What I thus try to do is to only count the number of "significant" > partners, where significance is defined on a per-actor basis. The > resulting index is very interesting for my data-set: I find a > statistical association between total number of trading partners > (weighted to total trade flows) and economic well-being. > > What is this centrality index called (as I assume the above has been > done before)? > > Yours, > Carl > -- To learn more about my evaluation book go to: http://www.oup-usa.org/isbn/0195141768.html My personal webpage: http://www-hsc.usc.edu/~tvalente/ --- Thomas W. Valente, PhD Director, Master of Public Health Program http://www.usc.edu/medicine/mph/ Department of Preventive Medicine School of Medicine University of Southern California 1000 S. Fremont Ave. Building A Room 5133 Alhambra CA 91803 phone: (626) 457-6678 fax: (626) 457-6699 email: [log in to unmask] _____________________________________________________________________ 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.