Table 1. Statistical performance metrics for diagnostic primer sets.

Primer set:	393	901	781	396	237
TP:	21	21	21	21	21
FP:	3	4	2	2	6
TN:	30	29	31	31	27
FN:	0	0	0	0	0
Sensitivity (recall):	1.00	1.00	1.00	1.00	1.00
Specificity:	0.91	0.88	0.94	0.94	0.82
PPV (precision):	0.88	0.84	0.91	0.91	0.78
FPR:	0.09	0.12	0.06	0.06	0.18
FDR:	0.13	0.16	0.09	0.09	0.22
F-measure:	0.93	0.91	0.95	0.95	0.88

The confusion matrix counts (TP: true positive; FP: false positive; TN: true negative; FN: false negative) derived from the experimental validation tests against unseen isolates of E. coli are presented. No false negatives were identified by any individual primer set. Derived performance measures are also indicated (PPV: positive predictive value; FPR: false positive rate; FDR: false discovery rate; F-measure: 2×recall×precision/(recall+precision)). All primer sets amplify all positive examples, and have specificity between 82–94%, with 9–22% false discovery rate.