Sensitivity analysis for optimizing meters' imprecision and bias. A. Low QC level. B. High QC level. The all-meter imprecision on the X-axis from left to right represented mean+3SD, mean+2SD, mean+1SD, mean, mean-1SD, mean-2SD, and mean-3SD. The different bins represented the 5th, 25th, 50th, 75th, and 95th percentiles of all-meter absolute bias, respectively. The biases were 0.00, 0.01, 0.04, 0.06, and 0.11 mmo/L for the low QC level; 0.08, 0.37, 0.80, 1.38, and 2.47 % for the high QC level. QC; quality control. SD; standard deviation. CV; correlation coefficient.