This chapter examines the links between Hierarchical Modelling of Species Communities (HMSC) outputs and the underlying community ecological processes. To do so, the chapter applies HMSC to simulated data generated from an agent-based model with known underlying assembly processes, and then assesses how those processes are captured from the patterns in the data. After simulating data with the spatial agent-based model, the chapter simulates two 'virtual ecologists' who sample data from the simulations, one applying a spatial study design and the other a temporal study design. While the main motivation of the chapter is to assess how community assembly processes translate into HMSC outputs, another motivation is to examine the robustness of HSMC to violations against structural model assumptions – namely, the data generated by the agent-based models violate some of the underlying assumptions of generalised linear mixed models and thus of HMSC. The chapter finishes by summarising what the virtual ecologists learned by applying HMSC to their data, particularly in light of the assembly processes that were used to simulate the data.