The present invention relates to a method and apparatus for event analysis in a communication (telecommunication or computer) system. In particular, the invention relates to a method and apparatus for analyzing events representing activity in the communication system. Embodiments provide a progressive technique for the analysis of the operation of a communication system. Embodiments provide a bottom-up approach by first detecting burst of events, and establishing causal relationships between events and system operation reports using detected event burst records representing the occurrence of burst behaviors in events in a system. Based on the causal relationships found, causes of a change in system operation may be identified by determining parameters associated with events of an event burst relevant to the change in system operation.