ASTM E1432-19
(Practice)Standard Practice for Defining and Calculating Individual and Group Sensory Thresholds from Forced-Choice Data Sets of Intermediate Size
Standard Practice for Defining and Calculating Individual and Group Sensory Thresholds from Forced-Choice Data Sets of<brk/> Intermediate Size
SIGNIFICANCE AND USE
6.1 Sensory thresholds are used to determine the potential of substances at low concentrations to impart odor, taste, skinfeel, etc. to some form of matter.
6.2 Thresholds are used, for example, in setting limits in air pollution, in noise abatement, in water treatment, and in food systems.
6.3 Thresholds are used to characterize and compare the sensitivity of individuals or groups to given stimuli, for example, in medicine, ethnic studies, and the study of animal species.
SCOPE
1.1 The definitions and procedures of this practice apply to the calculation of individual thresholds for any stimulus in any medium, from data sets of intermediate size, that is, consisting of more than 20 to 40 3-AFC presentations per individual. A group threshold may be calculated using 5 to 15 individual thresholds.
1.2 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.
1.3 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.
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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.
Designation:E1432 −19
Standard Practice for
Defining and Calculating Individual and Group Sensory
Thresholds from Forced-Choice Data Sets of
1
Intermediate Size
This standard is issued under the fixed designation E1432; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The purpose of this practice is to determine individual sensory thresholds for odor, taste, and other
modalities and, when appropriate, calculate group thresholds. The practice takes as its starting point
anysensorythresholddatasetofmorethan100presentations,collectedbyaforced-choiceprocedure.
TheusualprocedureistheThree-AlternativeForced-Choice(3-AFC)(seeISO13301),asexemplified
byDynamicTriangleOlfactometry.Asimilarpractice,PracticeE679,utilizeslimited-sizedatasetsof
50 to 100 3-AFC presentations, and is suitable as a rapid method to approximate group thresholds.
Collection of the data is not a part of this practice. The data are assumed to be valid; for example,
itisassumedthatthestimulusisdefinedproperly,thateachsubjecthasbeenfullytrainedtorecognize
thestimulusanddidindeedperceiveitwhenitwaspresentabovehisorhermomentarythreshold,and
that the quality of dilution medium did not vary.
It is recognized that precise threshold values for a given substance do not exist in the same sense
that values of vapor pressure exist. An assessor’s ability to detect a stimulus varies as a result of
random variations in factors such as alertness, attention, fatigue, events at the molecular level, health
status, etc., the effects of which can usually be described in terms of a probability function. At low
concentrations of an odorant or tastant, the probability of detection by a given individual is typically
0.0 and at high concentrations it is 1.0, and there is a range of concentrations in which the probability
of detection is between these limits. By definition, the threshold is the concentration for which the
probabilityofdetectionofthestimulusis0.5(thatis,50%abovechance,byagivenindividual,under
the conditions of the test).
Thresholds may be determined (1) for an individual (or for individuals one by one), and (2) for a
group (panel). While the determination of an individual threshold is a definable task, careful
consideration of the composition of the group is necessary to ensure the determined threshold
represents the group of interest.
Thereisalargedegreeofrandomerrorassociatedwithestimatingtheprobabilityofdetectionfrom
less than approximately 500 3-AFC presentations. The reliability of the results can be increased
greatly by enlarging the panel and by replicating the tests.
1. Scope medium, from data sets of intermediate size, that is, consisting
of more than 20 to 40 3-AFC presentations per individual. A
1.1 The definitions and procedures of this practice apply to
group threshold may be calculated using 5 to 15 individual
the calculation of individual thresholds for any stimulus in any
thresholds.
1
1.2 This standard does not purport to address all of the
This practice is under the jurisdiction of ASTM Committee E18 on Sensory
Evaluation and is the direct responsibility of Subcommittee E18.04 on Fundamen-
safety concerns, if any, associated with its use. It is the
tals of Sensory.
responsibility of the user of this standard to establish appro-
Current edition approved Aug. 1, 2019. Published September 2019. Originally
priate safety, health, and environmental practices and deter-
approved in 1991. Last previous edition approved in 2011 as E1432–04 (Reap-
proved 2011). DOI: 10.1520/E1432-19. mine the applicability of regulatory limitations prior to use.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E1432−19
1.3 This international standard was developed in accor- 4.1.1 model—an abstract or concrete analogy, usually
dance with internationally recognized principles on standard- mathematical, which represents in a useful way the functional
ization established in the Decision on Principles for the elements of a system or process. In short, the experimenter’s
Development of International Standards, Guides and Recom- theory of what is guiding the results observed.
mendations issued by the World Trade Organization Technical
4.1.2 statistical model—amodelassumingthattheprincipal
Barriers to Trade (TBT) Committee.
factor causing the results to deviate from the true value i
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E1432 − 04 (Reapproved 2011) E1432 − 19
Standard Practice for
Defining and Calculating Individual and Group Sensory
Thresholds from Forced-Choice Data Sets of
1
Intermediate Size
This standard is issued under the fixed designation E1432; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The purpose of this practice is to determine individual sensory thresholds for odor, taste, and other
modalities and, when appropriate, calculate group thresholds. The practice takes as its starting point
any sensory threshold data set of more than 100 presentations, collected by a forced-choice procedure.
The usual procedure is the Three-Alternative Forced-Choice (3-AFC) (see ISO 13301), as exemplified
by Dynamic Triangle Olfactometry. A similar practice, Practice E679, utilizes limited-size data sets of
50 to 100 3-AFC presentations, and is suitable as a rapid method to approximate group thresholds.
Collection of the data is not a part of this practice. The data are assumed to be valid; for example,
it is assumed that the stimulus is defined properly, that each subject has been fully trained to recognize
the stimulus and did indeed perceive it when it was present above his or her momentary threshold, and
that the quality of dilution medium did not vary.
It is recognized that precise threshold values for a given substance do not exist in the same sense
that values of vapor pressure exist. A panelist’sAn assessor’s ability to detect a stimulus varies as a
result of random variations in factors such as alertness, attention, fatigue, events at the molecular level,
health status, etc., the effects of which can usually be described in terms of a probability function. At
low concentrations of an odorant or tastant, the probability of detection by a given individual is
typically 0.0 and at high concentrations it is 1.0, and there is a range of concentrations in which the
probability of detection is between these limits. By definition, the threshold is the concentration for
which the probability of detection of the stimulus is 0.5 (that is, 50 % above chance, by a given
individual, under the conditions of the test).
Thresholds may be determined (1) for an individual (or for individuals one by one), and (2) for a
group (panel). While the determination of an individual threshold is a definable task, careful
consideration of the composition of the group is necessary to ensure the determined threshold
represents the group of interest.
There is a large degree of random error associated with estimating the probability of detection from
less than approximately 500 3-AFC presentations. The reliability of the results can be increased
greatly by enlarging the panel and by replicating the tests.
1. Scope
1.1 The definitions and procedures of this practice apply to the calculation of individual thresholds for any stimulus in any
medium, from data sets of intermediate size, that is, consisting of more than 20 to 40 3-AFC presentations per individual. A group
threshold may be calculated using 5 to 15 individual thresholds.
1.2 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1
This practice is under the jurisdiction of ASTM Committee E18 on Sensory Evaluation and is the direct responsibility of Subcommittee E18.04 on Fundamentals of
Sensory.
Current edition approved Aug. 1, 2011Aug. 1, 2019. Published August 2011September 2019. Originally approved in 1991. Last previous edition approved in 20042011
as E1432E1432 – 04–04 . DOI: 10.1520/E1432-04R11. (Reapproved 2011) . DOI: 10.1520/E1432-19.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E1432 − 19
1.3 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
...
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