The determination of the ratio of hemoglobin A2 prime compared to total hemoglobin present in a sample. The measurement may be expressed as a ratio or percentage. [ NCI ]. The trait is Experimental Factor Ontology entry EFO_0009211 (Hemoglobin A2 Prime to Total Hemoglobin Ratio Measurement). Also known as: HBA2PHB, Hemoglobin A2 Prime/Total Hemoglobin.