Table 3. Comparison of result reporting schemes.

We evaluated three different reporting schemes. The single threshold scheme uses a single numerical threshold to determine whether a subject has a bacterial infection in the bacterial vs. non-bacterial model or a viral infection in the viral vs. non-viral model. This single threshold allows for all subjects to be classified. The Quartile scheme uses multiple thresholds to assign subjects into probability bands. The reported PPA and NPA values focus on the top and bottom quartiles, therefore representing 50% of the cohort. The equivocal zone model allows for a probability band in which no call can be made. The equivocal zone thresholds for bacterial vs. non-bacterial and viral vs. non-viral classification were selected to exclude no more than 15% of the cohort.

	Single Threshold			Quartiles			Equivocal Zone
	PPA	NPA	% cohort	PPA	NPA	% cohort	PPA	NPA	% cohort
Training Cohort-Bacterial vs. Non-Bacterial Model	85.3	81.4	100	100	92.4	50	85.4	86.2	85
Validation Cohort-Bacterial vs. Non-Bacterial Model	79.1	81.0	100	94.0	90.1	50	83.2	83.1	88
Training Cohort-Viral vs. Non-Viral Model	85.9	86.0	100	96.7	98.3	50	84.5	92.3	85
Validation Cohort-Viral vs. Non-Viral Model	89.0	84.7	100	96.7	94.9	50	81.5	91.8	85