Table 3.

Precision of the vancomycin bioassay

Vancomycin concentration (mg/L)	Inhibition zone diameters (mean in mm ± SD)	Coefficient of variation (%) Intra-day	Coefficient of variation (%) Inter-day
128	18.00 ± 0.04	8.3	10.3
64	16.33 ± 0.02	5.6	10.5
32	14.16 ± 0.11	11.0	1.0
16	11.62 ± 0.37	7.4*	2.3
8	9.59 ± 0.00	4.6	6.5

*An outlier value was excluded from the calculations (we only used five data to compute the CV)