Parkes et al. developed an error grid to analyze the clinical significance of the bias between blood glucose
system results and lab reference results. For analysis, data points are assigned into one of the five
Zones (A-E) on the error grid. Results, or data points, falling into Zones A and B are defined as clinically
acceptable, where any observed bias from lab results would not lead to treatment decisions that may
put a patient at risk. As the bias, or difference, increases (Zones C, D, and E), there is greater risk of
under treating or over treating a patient based on the glucose system result.