The problem with total error models in establishing performance specifications and a simple remedy

Abstract

AbstractA recent issue in this journal revisited performance specifications since the Stockholm conference. Of the three recommended methods, two use total error models to establish performance specifications. It is shown that the most commonly used total error model – the Westgard model – is deficient, yet even more complete models fail to capture all errors that comprise total error. Moreover, total error models are often set at 95% of results, which leave 5% of results as unspecified. Glucose meter performance standards are used to illustrate these problems. The Westgard model is useful to asses assay performance but not to set performance specifications. Total error can be used to set performance specifications if the specifications include 100% of the results.