Standard Test Method for Unipolar Magnitude Estimation of Sensory Attributes

Importancia y uso:

5.1 Magnitude estimation may be used to measure and compare the intensities of attributes of a wide variety of products.

5.2 Magnitude estimation provides a large degree of flexibility for both the experimenter and the assessor. Once trained in magnitude estimation, assessors are generally able to apply their skill to a wide variety of sample types and attributes, with minimal additional training.

5.3 Magnitude estimation is not as susceptible to end-effects as interval scaling techniques. These can occur when assessors are not familiar with the entire range of sensations being presented. Under these circumstances, assessors may assign an early sample to a category which is too close to one end of the scale. Subsequently, they may “run out of scale” and be forced to assign perceptually different samples to the same category. This should not occur with magnitude estimation, as, in theory, there are an infinite number of categories.

5.4 Magnitude estimation is one frequently used technique that permits the representation of data in terms of Stevens' power law.

5.5 The disadvantages of magnitude estimation arise primarily from the requirements of the data analysis.

5.5.1 Permitting each assessor to choose a different numerical scale may produce significant assessor effects. This disadvantage can be overcome in a number of ways, as follows. The experimenter must choose the approach most appropriate for the circumstances.

5.5.1.1 Experiments can be designed such that analysis of variance can be used to remove the assessor effects and interactions.

5.5.1.2 Alternatively, assessors can be forced to a common scale, either by training or by use of external reference samples with assigned values (modulus).

5.5.1.3 Finally, each assessor's data can be brought to a common scale by one of a variety of normalizing methods.

5.5.2 Logarithms must be applied before carrying out data analysis. This becomes problematic if values are near threshold, as a logarithm of zero cannot be taken (see 11.2.1).

5.6 Magnitude estimation should be used:

5.6.1 When end-effects are a concern, for example when assessors are not familiar with the entire range of sensations being presented.

5.6.2 When Stevens' power law is to be applied to the data.

5.6.3 Generally, in central location testing with assessors trained in the technique. It is not appropriate for home use or mall intercept testing with consumers.

5.7 This test method is only meant to be used with assessors who are specifically trained in magnitude estimation. Do not use this method with untrained assessors or untrained consumers.

Subcomité:

E18.04

Referida por:

E1207-14R22

Volúmen:

14.03

Número ICS:

67.240 (Sensory analysis)

Palabras clave:

agricultural products; beverages; color; estimation; feel; food products; magnitude estimation; odor or water pollution; odors; perfumes; scaling; sensory analysis; sound; taste; tobacco ;