***** To join INSNA, visit http://www.insna.org ***** Bob, Another way of analyzing this might be to use an "agent-based-modelling" approach like that used in NetLogo ( http://ccl.northwestern.edu/netlogo/ ). This is a free application available from Northwestern Univ and it has model libraries as part of the package. One of the sample models is called "Virus on a Network". There are also generic diffusion models for networks and 'infection' models. Regards, Mike. _____________________________________________________________________ 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.