Passive verification, comprising, receiving a representation of an electronic design comprised at least in part of at least system having at least one subsystem which is analog, collecting at least one input subsystem level data, having at least one input subsystem signal marker, collecting at least one output subsystem level data, having at least one output subsystem signal marker and analyzing at least one measure of at least one of the at least one input subsystem signal marker and at least one output subsystem signal marker.