scope:

EP21 provides guidance for understanding, estimating, and evaluating total analytical error (TAE) for quantitative medical laboratory measurement procedures. This guidance is suitable for both commercial products as well as laboratory-developed tests (LDTs). It is particularly useful for medical laboratories to assess the performance of measurement procedures intended to be put into service, relative to goals for allowable measurement error.

Through EP21, users will learn the limitations of traditional estimates of TAE that added independent point estimates of bias and imprecision, accounting for all sources of error including those due to nonlinearity, nonspecificities, lot-to-lot variations in reagent performance, etc. Users will learn how to:

• Describe the difference between TAE and total error, which includes pre- and postexamination (pre- and postanalytical) components, and why EP21 focuses only on the former.

• Explain the various available sources for establishing allowable total error (ATE) goals, also called total error allowable.

• Discuss considerations for setting ATE limits, including selection of appropriate subintervals.

• Design an experiment to measure TAE and determine if performance goals were met.

The intended users of this guideline are developers of in vitro diagnostic (IVD) reagents, regulatory authorities, and medical laboratory personnel