QUALITY-CONTROL (QC) PERFORMANCE-MEASURES AND THE QC PLANNING PROCESS

Numerous outcome measures can be used to characterize and compare the performance of alternative quality-control (QC) strategies. The perfor mance measure traditionally used in the QC planning process is the pro bability of rejecting an analytical run when a critical out-of-control error condition exists. Another performance measure that naturally fi ts within the total allowable error paradigm is the probability that a reported test result contains an analytical error that exceeds the to tal allowable error specification. In general, the out-of-control erro r conditions associated with the greatest chance of reporting an unacc eptable test result are unrelated to the traditionally defined ''criti cal'' error conditions. If the probability of reporting an unacceptabl e test result is used as the primary performance measure, worst-case Q C performance can be determined irrespective of the magnitude of any o ut-of-control error condition that may exist, thus eliminating the nee d for the concept of a ''critical'' out-of-control error.