ISO International Standard

This document specifies a procedure for statistically analysing data from forced-choice sensory discrimination tests, such as the triangle, duo-trio, 3-AFC, 2-AFC, in which after every trial of the discrimination test the decision can be made to stop testing and declare a difference, to stop testing and declare no difference, or to continue testing.

The sequential method often allows for a decision to be made after fewer trials of the discrimination test than would be required by conventional approaches that use predetermined numbers of assessments.

The method is effective for:

a) determining that either:

1. a perceptible difference results; or
2. a perceptible difference does not result when, for example, a change is made in ingredients, processing, packaging, handling or storage;

b) selecting, training and monitoring assessors.

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