ASTM E2139-05(2018)

5.1 This overall difference test method is used when the test objective is to determine whether a sensory difference exists or does not exist between two samples. It is also known as the simple difference test.

5.2 The test is appropriate in situations where samples have extreme intensities, give rapid sensory fatigue, have long lingering flavors, or cannot be consumed in large quantities, or a combination thereof.

5.3 The test is also appropriate for situations where the stimulus sites are limited to two (for example, two hands, each side of the face, two ears).

5.4 The test provides a measure of the bias where judges perceive two same products to be different.

5.5 The test has the advantage of being a simple and intuitive task.

1.1 This test method describes a procedure for comparing two products.

1.2 This test method does not describe the Thurstonian modeling approach to this test.

1.3 This test method is sometimes referred to as the simple-difference test.

1.4 A same-different test determines whether two products are perceived to be the same or different overall.

1.5 The procedure of the test described in this test method consists of presenting a single pair of samples to each assessor. The presentation of multiple pairs would require different statistical treatment and it is outside of the scope of this test method.

1.6 This test method is not attribute-specific, unlike the directional difference test.

1.7 This test method is not intended to determine the magnitude of the difference; however, statistical methods may be used to estimate the size of the difference.

1.8 This test method may be chosen over the triangle or duo-trio tests where sensory fatigue or carry-over are a concern, or where a simpler task is needed.

1.9 This standard may involve hazardous materials, operations, and equipment. 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.10 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.