# QC Selection Grid, Square 6

## MULTIRULE CHOICE:

You have a moderate number of problems, but the medically important errors are relatively large and therefore easy to detect. You should use a three rule multirule procedure with N=2 for within run detection and add a 41s rule to provide a more sensitive warning rule that works across two runs (R=2). The power curves below show the rejection characteristics within a run (R=1) and across two runs (R=2):

Plot your critical-error on the x-axis of this power function graph. Draw a vertical line from that point to intersect the power curves. Where the curves and critical-error meet indicates how much error detection each control rule will provide.