1. An analysis system for analyzing at least one continuous query for at least one input data stream, wherein the at least one input data stream comprises a sequence of events captured by at least one sensor, and wherein the analysis system comprises: an analyzer configured to execute the at least one continuous query and at least one modified continuous query on the at least one input data stream, compare at least one output data stream produced by the at least one continuous query with at least one second output data stream produced by the at least one modified continuous query, and indicate at least one difference between the at least one output data stream and the at least one second output data stream; wherein the analyzer is further configured to synchronize the execution of the at least one continuous query and the at least one modified continuous query; and wherein the system further comprises a stream logger configured to record the at least one output data stream into at least one recorded output data stream, wherein the analyzer is configured to select at least one event in the at least one recorded output data stream and to provide access to the corresponding at least one event in at least one recorded input data stream.