Introduction

Abstract

Consider the problems of assessing the acceptability of a new or generic process, methodology, and/or formulation in areas of lab performance, instrument/assay validation or method comparisons, statistical process control, goodness-of-fit, and individual bioequivalence. The common theme is to assess the agreement between observations (Y ) and their corresponding target values (X). Target values may be considered random or fixed. Commonly used random target values are the gold standard measurements, which are proven and widely acceptable. Commonly used fixed target values are the expected or known values. We might be interested in comparing two methods without a designated gold standard method. Sometimes, we may also be interested in comparing a newly developed assay that is alleged to be more precise and accurate than a designated gold standard assay. Within a method, we might be interested in comparing technicians/times/reagents.