Bias, its minimization or circumvention to simplify internal quality assurance

Abstract Several concepts of analytical bias and remedies to minimize bias have been suggested with the ultimate goal to disregard it. Short-term bias (within one control cycle) should be treated as a random error if it is less than the permissible limits. Long-term bias should be eliminated if it is known or circumvented by estimating intra-laboratory reference limits (RLs). Consequently, analytical uncertainty could be reduced to permissible imprecision. Then, models combining imprecision and bias would become irrelevant, and the numerical value of total analytical error would become identical with imprecision. The purpose of the present report is to simplify quality assurance schemes considerably by disregarding bias either by estimating RLs or by verifying the applied reference limits (checking the transferability) as requested by ISO and CLSI.