Coulter Electronics, Inc.

Frank C Anderson

Dean E Twedt

An improved procedure for statistically evaluating the performance, precision and/or accuracy, of at least one analytical instrument in a pool of like or substantially like instruments by comparing the performance of the one instrument located in one laboratory with the performance of like instruments in other laboratories. The procedure includes the step of quantitatively analyzing a reference or control specimen of known constituents by each instrument in the pool and collecting the resultant data from the one instrument in the pool and of the pool instruments. The mean data from the one instrument and of the pool instruments are mathematically correlated in a series of statistical equations for computing a novel, sensitive index known as the 'Instrument Performance Index' or IPI. This IPI can be tabulated and/or graphically displayed, preferably as a single point in a Cartesian coordinate system, whereby an operator can tell at a glance the performance level with respect to both precision and accuracy of the one instrument in the pool. The ultimate IPI is composed of a novel Coefficient of Variation Index (CVI), which is a valuable measure of instrument precision, and the Standard Deviation Index (SDI), which is a measure of performance accuracy. Both the CVI and SDI are derived values according to the invention and are capable of tabulation and display.

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Hialeah, FL, United States of America

Frank C Anderson