1.1 This test method covers a procedure for determining whether a perceptible sensory difference exists between samples of two products or to estimate the magnitude of the perceptible difference.

1.2 This test method applies whether a difference may exist in a single sensory attribute or in several.

1.3 This test method is applicable when the nature of the difference between the samples is unknown. The attribute(s) responsible for the difference are not identified.

1.4 The tetrad test is more efficient statistically than the triangle test (Test Method E1885) or the duo-trio test (Test Method E2610).

1.5 The tetrad method involves the evaluation of four samples. When the products being tested cause excessive sensory fatigue, carryover, or adaptation, methods that involve the evaluation of fewer samples (same-different, triangle test, etc.) may be preferred.

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.