Standard Test Method for Sensory Analysis—Tetrad Test

Abstract

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 the products are perceptibly different versus that the products are sufficiently similar to be used interchangeably. Only the selected values of α, β, and δ or Pd change. If the objective of the test is to determine if there is a perceptible difference between two products, then initially the products are assumed to be indistinguishable (for example, HO: δ or Pd = 0) and the data are examined to determine if the assumption can be rejected (that is, conclude that the products are perceptively different). If the objective is to determine if the two products are sufficiently similar to be used interchangeably, then initially the products are assumed to be meaningfully different (for example, HO: δ or Pd > the value chosen to represent a meaningful difference) and the data are examined to determine if the assumption can be rejected (that is, conclude that the samples are sufficiently similar to be used interchangeably). 5.3 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.