5.1 The test method is effective for the following test objectives:

5.1.1 To determine whether a perceptible difference results or a perceptible difference does not result, for example, when a change is made in ingredients, processing, packaging, handling, or storage; or

5.1.2 To select, train, and monitor assessors.

5.2 The test method itself does not change whether the purpose of the test is to determine that two products are perceptibly different versus that the products are not perceptibly different. Only the selected values of δ, α, and β change. If the objective of the test is to determine if the two products are sufficiently similar to be used interchangeably, then the value selected for β is typically smaller than the value selected for α and the value of δ is selected to define “sufficiently similar.”

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.