Estimating the linear analytic range

Although many methods have been proposed to verify assay linearity, or to test for nonlinearity, there are few, if any, statistically sound methods to establish an assay's linear range. In this article, we propose a simple and statistically sound method for initially establishing an assay's linear range as a paradigm for standardization of manufacturers' claims of assay linearity. Simulations verify that the method outperforms using (Pearson's) coefficient of determination (r2) to estimate the linear range, consistently yielding estimates for the linear range which are more accurate. In addition, the method permits the addition of tolerance limits when a certain amount of nonlinearity is acceptable clinically.