1. A method for generating a decision graph from event stream data for predicting events with event labels chosen from a plurality of event labels, wherein the event stream data comprises a plurality of events, and wherein each of the plurality of events comprises an event label and an associated time stamp, the method comprising: generating leaf nodes for the decision graph, wherein each of the leaf nodes comprises a rate parameter of a predicted event; and generating decision nodes for the decision graph, wherein each of the decision nodes comprises a question about a predicted event or historical events, or both, wherein the decision nodes are parents to the leaf nodes, and wherein the decision graph is based on sharing structure and parameters among labels.