ASTM E2935-15

4.1 Laboratories conducting routine testing have a continuing need to evaluate test result bias, to evaluate changes for improving the test process performance, or to validate the transfer of a test method to a new location or apparatus. In all situations it must be demonstrated that any bias or innovation will have negligible effect on test results for a characteristic of a material. This standard provides statistical methods to confirm that the mean test results from a testing process are equivalent to those from a reference standard or another testing process, where equivalence is defined as agreement within prescribed limits, termed equivalence limits.

4.2 This practice currently deals only with the equivalence of population means. In this standard, a Note 1: The equivalence concept can also apply to population parameters other than means, such as precision, stated as variances, standard deviations, or relative standard deviations (coefficients of variation), linearity, sensitivity, specificity, etc.

4.3 The data analysis for equivalence testing of population means in this practice uses a statistical methodology termed the two one-sided tests (TOST) procedure which shall be described in detail in this standard (see X1.1). The TOST procedure will be adapted to the type of objective and experiment design selected.

1.1 This practice provides statistical methodology for conducting equivalence testing on numerical data from two sources to determine if their true means differ by no more than predetermined limits.

1.2 Applications include (1) equivalence testing for bias against an accepted reference value, (2) determining equivalence of two test methods, test apparatus, instruments, reagent sources, or operators within a laboratory, and (3) equivalence of two laboratories in a method transfer.

1.3 The current guidance in this standard applies only to experiments conducted on a single material. Guidance is given for determining the amount of data required for an equivalence trial.

1.4 The statistical methodology for determining equivalence used is the two one-sided tests (TOST) procedure. The control of risks associated with the equivalence decision is discussed.

1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.