The graph below shows the Parkes error grid in blue. Each zone in the Parkes error grid shows increasing patient harm with the innermost zone A having no harm. The zones (unlabeled) start with A (innermost) and go to D or E.
The red lines are the POCT 12-A3 standard. The innermost line should contain 95% of the results. Since no more than 2% can be outside of the outermost red lines, these outermost red lines should contain 98% of the data.
The red lines correspond roughly with the A zone of the Parkes error grid – the region of no patient harm.
Of course the problem is that in the CLSI guideline, 2% of the results are allowed to occur in the higher zones of the Parkes error grid corresponding to severe patent harm.