14. The system of claim 13 , wherein the statistics for the at least one of the variable nodes are updated by enabling a child variable node to inherit a noisy version of the latent event score of a parent variable node of the child node.
13. A system comprising: one or more processors; memory; a monitor component maintained at least in part in the memory and executed at least in part by the one or more processors to monitor a stream of user click events occurring at the system, each event being associated with a plurality of features describing the event, at least some of the plurality of features being related in a hierarchical manner; a graphical data component maintained at least in part in the memory and executed at least in part by the one or more processors to create a graphical data structure comprising layers of parent and child variable nodes connected by edges, weights associated with the features being represented by variable nodes and the variable nodes being connected such that sequences of connected variable nodes represent the hierarchical relations between features, each variable node being associated with statistics describing a probability distribution representing a latent event score; a training engine maintained at least in part in the memory and executed at least in part by the one or more processors to update the statistics for at least one of the variable nodes on the basis of the monitoring; and a prediction engine maintained at least in part in the memory and executed at least in part by the one or more processors to predict an event related to a simultaneous scope search using the graphical data structure.