Algorithm 2: Stochastic Compartmental Contagion Process 1 S % of all nodes are selected at random to be initially affected. 2 Until B % population incidence: 3 Repeat T times: a Successively select q$_{ij}$ neighbors. b If neighbor j ′ is already affected, do nothing. If not, affect with probability p$_{0}$ . a Successively select q$_{ij}$ neighbors. b If neighbor j ′ is already affected, do nothing. If not, affect with probability: p$_{0}$ for those in unexposed clusters. p$_{1}$ for those in exposed clusters. For each affected node j (in random order): For each affected node j (in random order): Each network in our simulation comprises eight blocks. We simulate networks using two types of block structure, random and heterogeneous. For a complete description of the block structures used, see Section 2 in supplementary material. A diagram of these structures is shown in Figure 1. To match the approximate size of the empirical dataset used in the microfinance application, each simulated study consists of a contagion process propagating on m = 48 clusters (networks) of sizes ranging from n = 120 to 280, with an average size of size 200, totaling 9600 individuals. Block Structure Simulation Setting Parameters 10