<status value="active"/> <experimental value="false"/> <date value="2014-03-26"/> <description value="A set of codes that defines how a set of values are summarized in an aggregated computation, for use with sets of values do describe which aggregated statistic functions are to be applied (e.g., average, mode, min, max, standard deviation, variance)."/> <compose> <include> <system value="http://terminology.hl7.org/CodeSystem/v3-ObservationMethod"/> <filter> <property value="concept"/> <op value="is-a"/> <value value="_ObservationMethodAggregate"/> </filter> </include> </compose> </ValueSet>