The news is full of widely (and wildly) varying estimates of the scale and scope of human trafficking. This is partly because vulnerable individuals are often hidden and are therefore hard to count.

Network sampling emerged as a set of methods for drawing statistically valid samples of hard-to-reach populations. The first form of network sampling, multiplicity sampling, involved asking ...

What are the possibilities of snowball sampling, if one desires valid statistical inference without making probabilistic assumptions on the network structure? In a critical review of the possibilities ...