***** To join INSNA, visit http://www.insna.org ***** Barry, I know it exists because I used it once with a student -- which doesn't mean I still have it (or that I remember where I got it it). At the time there was nothing remarkably difficult about getting it. It was point to point for a year with passenger as the unit of analysis. One big validity problem: In the real world passenger passenger traffic is not a monotone function of either distance or real traffic: There isn't much air traffic (some but not much) between extremely nearby destinations: take a cab. Joel _____________________________________________________________________ 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.