*N* nodes at random are selected from the graph. All edges among those *n* nodes are added to the new graph. Unattached nodes are then dropped.

This is one of the simplest sampling techniques for obtaining a subset of the data to work with.

S. H. Lee, P-J. Kim, and H. Jeong. (2006) Statistical properties of sampled networks. Physical Review E 73.

http://dx.doi.org/10.1103/PhysRevE.73.016102