DEFINING AND LOCATING CORES AND BOUNDARIES OF SOCIAL NETWORKS

We propose a general procedure for locating the boundary of a network and a second, related, procedure for discerning the boundaries within a network. The first is an expanding (snowball) selection procedure. T he second requires the specification of two critical parameters: the v alue of k for a k-core and the threshold, w, for the quantitative magn itude of network ties. The use of these parameters generates a sequenc e of nested cores. Single sector and multi-sector social service inter -agency networks are used to illustrate the procedures.