11. The method of claim 9 , wherein processing each PHR of the plurality of PHRs further includes identifying a second event-concept pair associated with the desired event-concept pair, and finding a relationship corresponding to the desired event-concept pair and the second event-concept pair, and wherein finding an aggregate result includes aggregating the plurality of relationships corresponding to the plurality of PHRs.
11. The method of claim 9 , wherein processing each PHR of the plurality of PHRs further includes identifying a second event-concept pair associated with the desired event-concept pair, and finding a relationship corresponding to the desired event-concept pair and the second event-concept pair, and wherein finding an aggregate result includes aggregating the plurality of relationships corresponding to the plurality of PHRs. 12. The method of claim 11 , wherein the relationship is a difference between the time stamp of the desired event-concept and the time stamp of the second event concept.