1. A system, comprising: interface hardware to receive current behavior data representing events occurring within a process; and at least one processor to generate a display of a reference statistical model of the process, along with a graph representing current behavior of the process, wherein the reference statistical model is to be displayed as a hierarchical, segmented time series event stream graph, and wherein the processor is to accept requests to display further detail in a hierarchy respecting discrepancies between the reference statistical model and the current behavior.