Semi-Empirical Equations for Interlaboratory Studies in Water Chemistry

Abstract

Recently, a number of semi-empirical equations have been used effectively to assist in the design and the analysis of interlaboratory studies for water quality parameters. In general, these equations are simple and straightforward in their applications to environmental data, covering a wide variety of chemical and physical water quality variables.

The equations permit: (a) the calculation of the minimum number of laboratories that should participate in an interlaboratory quality control study; (b) the estimation of the between-laboratory variability in interlaboratory QC studies; and, (c) the determination of the bivariate relationship between paired data points in a Youden plot.

Key Words:

• Semi-empirical equations
• interlaboratory quality control
• between-laboratory variability
• within-laboratory variability
• Youden plot
• contour ellipse