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ASTM E2164-01

(Test Method)

Standard Test Method for Directional Difference Test

Standard Test Method for Directional Difference Test

SIGNIFICANCE AND USE
The directional difference test determines with a given confidence level whether or not there is a perceivable difference in the intensity of a specified attribute between two samples, for example, when a change is made in an ingredient, a process, packaging, handling, or storage.
The directional difference test is inappropriate when evaluating products with sensory characteristics that are not easily specified, not commonly understood, or not known in advance. Other difference test methods such as the same-different test should be used.
A result of no significant difference in a specific attribute does not ensure that there are no differences between the two samples in other attributes or characteristics, nor does it indicate that the attribute is the same for both samples. It may merely indicate that the degree of difference is too low to be detected with the sensitivity (α, β, and Pmax) chosen for the test.
5.3.1 The method itself does not change whether the purpose of the test is to determine that two samples are perceivably different versus that the samples are not perceivably different. Only the selected values of Pmax, α, and β change. If the objective of the test is to determine if the two samples are perceivably different, then the value selected for α is typically smaller than the value selected for β. If the objective is to determine if no perceivable difference exists, then the value selected for β is typically smaller than the value selected for α and the value of Pmax needs to be stated explicitly.
SCOPE
1.1 This Test Method covers a procedure for comparing two products using a two-alternative forced-choice task.
1.2 This method is sometimes referred to as a paired comparison test or as a 2-AFC (alternative forced choice) test.
1.3 A directional difference test determines whether a difference exists in the perceived intensity of a specified sensory attribute between two samples.
1.4 Directional difference testing is limited in its application to a specified sensory attribute and does not directly determine the magnitude of the difference for that specific attribute. Assessors must be able to recognize and understand the specified attribute. A lack of difference in the specified attribute does not imply that no overall difference exists.
1.5 This test method does not address preference.
1.6 A directional difference test is a simple task for assessors, and is used when sensory fatigue or carryover is a concern. The directional difference test does not exhibit the same level of fatigue, carryover, or adaptation as multiple sample tests such as triangle or duo-trio tests. For detail on comparisons among the various difference tests, see referencess. (1),  (2), and (3).
1.7 The procedure of the test described in this document consists of presenting a single pair of samples to the assessors.
1.8 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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

Status
Historical
Publication Date
09-Oct-2001
ICS
19.020 - Test conditions and procedures in general
Technical Committee
E18 - Sensory Evaluation
Drafting Committee
E18.04 - Test Methods
Current Stage
Ref Project

Relations

Replaced By
ASTM E2164-01(2007) - Standard Test Method for Directional Difference Test
Effective Date
01-Sep-2007
Referred By
ASTM E3093-20 - Standard Guide for Structured Small Group Product Evaluations
Effective Date
10-Oct-2001
Referred By
ASTM E460-21 - Standard Practice for Determining Effect of Packaging on Food and Beverage Products During Storage
Effective Date
10-Oct-2001
Referred By
ASTM E1958-22 - Standard Guide for Sensory Claim Substantiation
Effective Date
10-Oct-2001
Referred By
ASTM E3261-21 - Standard Guide for Odor Evaluation of Products and Materials Under Controlled Conditions With Trained Panel
Effective Date
10-Oct-2001
Referred By
ASTM E2263-12(2018) - Standard Test Method for Paired Preference Test
Effective Date
10-Oct-2001
Referred By
ASTM D5237-14(2019) - Standard Guide for Evaluating Fabric Softeners
Effective Date
10-Oct-2001

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ASTM E2164-01 - Standard Test Method for Directional Difference Test
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Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E 2164 – 01
Standard Test Method for
1
Directional Difference Test
This standard is issued under the fixed designation E 2164; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope E 1871 Practice for Serving Protocol for Sensory Evalua-
3
tion of Foods and Beverages
1.1 ThisTest Method covers a procedure for comparing two
2.2 ASTM Publications:
products using a two-alternative forced-choice task.
Manual 26 Sensory Testing Methods, 2nd Edition
1.2 This method is sometimes referred to as a paired
STP 758 Guidelines for the Selection and Training of
comparison test or as a 2-AFC (alternative forced choice) test.
Sensory Panel Members
1.3 A directional difference test determines whether a dif-
STP 913 Guidelines. Physical Requirements for Sensory
ference exists in the perceived intensity of a specified sensory
Evaluation Laboratories
attribute between two samples.
2.3 ISO Standard:
1.4 Directional difference testing is limited in its application
ISO 5495 Sensory Analysis—Methodology—Paired Com-
to a specified sensory attribute and does not directly determine
parison
the magnitude of the difference for that specific attribute.
Assessors must be able to recognize and understand the
3. Terminology
specifiedattribute.Alackofdifferenceinthespecifiedattribute
3.1 For definition of terms relating to sensory analysis, see
does not imply that no overall difference exists.
Terminology E 253, and for terms relating to statistics, see
1.5 This test method does not address preference.
Terminology E 456.
1.6 A directional difference test is a simple task for asses-
3.2 Definitions of Terms Specific to This Standard:
sors, and is used when sensory fatigue or carryover is a
3.2.1 a (alpha) risk—the probability of concluding that a
concern. The directional difference test does not exhibit the
perceptibledifferenceexistswhen,inreality,onedoesnot(also
same level of fatigue, carryover, or adaptation as multiple
known as type I error or significance level).
sample tests such as triangle or duo-trio tests. For detail on
3.2.2 b (beta) risk—the probability of concluding that no
comparisons among the various difference tests, see referen-
2 perceptible difference exists when, in reality, one does (also
cess. (1), (2), and (3).
known as type II error).
1.7 The procedure of the test described in this document
3.2.3 one-sided test—a test in which the researcher has an a
consists of presenting a single pair of samples to the assessors.
priori expectation concerning the direction of the difference. In
1.8 This standard does not purport to address all of the
this case, the alternative hypothesis will express that the
safety concerns, if any, associated with its use. It is the
perceived intensity of the specified sensory attribute is greater
responsibility of the user of this standard to establish appro-
(that is,A>B) (or lower (that is,A priate safety and health practices and determine the applica-
the other.
bility of regulatory limitations prior to use.
3.2.4 two-sided test—a test in which the researcher does not
2. Referenced Documents have any a priori expectation concerning the direction of the
difference. In this case, the alternative hypothesis will express
2.1 ASTM Standards:
that the perceived intensity of the specified sensory attribute is
E 253 Terminology Relating to Sensory Evaluation of Ma-
3
different from one product to the other (that is, AfiB).
terials and Products
4
3.2.5 common responses—for a one-sided test, the number
E 456 Terminology Relating to Quality and Statistics
of assessors selecting the sample expected to have a higher
intensity of the specified sensory attribute. Common responses
couldalsobedefinedintermsoflowerintensityoftheattribute
1
This test method is under the jurisdiction ofASTM Committee E18 on Sensory
if it is more relevant. For a two-sided test, the larger number of
Evaluation and is the direct responsibility of Subcommittee E18.04 on Fundamen-
assessors selecting sample A or B.
tals of Sensory.
Current edition approved Oct. 10, 2001. Published January 2002.
3.2.6 P —Atest sensitivity parameter established prior to
max
2
The boldface numbers in parentheses refer to the list of references at the end of
testing and used along with the selected values of a and b to
this standard.
3 determine the number of assessors needed in a study. P is
Annual Book of ASTM Standards, Vol. 15.08 max
4
Annual Book of ASTM Standards, Vol. 14.02 the proportion of common responses that the researcher wants
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West C
...

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5.1.2 The regression technique described in this practice can also be used to determine a limit of quantitation specific for a single laboratory (LLOQ). The limit thus quantified for one laboratory is defined by this standard as the laboratory limit of quantitation (LLOQ).  
5.1.3 It should be noted that since differences in repeatability testing capabilities between different laboratories can exist, therefore, LLOQ determined at a single laboratory can be different than the PLOQ determined for the test method.  
5.2 Values below the PLOQ are deemed by this practice to be too uncertain for meaningful use in commerce, or in regulatory activities.
SCOPE
1.1 This practice covers the use of standard regression techniques and data from an interlaboratory study to determine a lower quantitative limit for a test method. This determined lower limit represents the numerical limit at or above which the test results are considered to be quantitatively meaningful for commerce or regulatory activities by this practice. It is defined by this standard as the pooled limit of quantitation (PLOQ) for the test method.  
1.2 This practice is applicable to test methods that are capable of producing numerical test results close to zero. Examples are those test methods that determine quantitatively the concentration of analyte(s) near zero.  
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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ASTM
ASTM E691-23(Practice)
Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

ABSTRACT
This practice describes the techniques for planning, conducting, analyzing, and treating the results of an interlaboratory study (ILS) of a test method. The statistical techniques described in this practice provide adequate information for formulating the precision statement of a test method. This practice is also concerned exclusively with test methods which yield a single numerical figure as the test result, although the single figure may be the outcome of a calculation from a set of measurements. ASTM regulations require precision statements in all test methods in terms of repeatability and reproducibility and knowledge of the test method precision is useful in commerce and in technical work when comparing test results against standard values or between data sources.
SIGNIFICANCE AND USE
4.1 ASTM regulations require precision statements in all test methods in terms of repeatability and reproducibility. This practice may be used in obtaining the needed information as simply as possible. This information may then be used to prepare a precision statement in accordance with Practice E177. Knowledge of the test method precision is useful in commerce and in technical work when comparing test results against standard values (such as specification limits) or between data sources (different laboratories, instruments, etc.).  
4.1.1 When a test method is applied to a large number of portions of a material that are as nearly alike as possible, the test results obtained will not all have the same value. A measure of the degree of agreement among these test results describes the precision of the test method for that material. Numerical measures of the variability between such test results provide inverse measures of the precision of the test method. Greater variability implies smaller (that is, poorer) precision and larger imprecision.  
4.1.2 Precision is reported as a standard deviation, coefficient of variation (relative standard deviation), variance, or a precision limit (a data range indicating no statistically significant difference between test results).  
4.1.3 This practice is designed only to estimate the precision of a test method. However, when accepted reference values are available for the property levels, the test result data obtained according to this practice may be used in estimating the bias of the test method. For a discussion of bias estimation and the relationships between precision, bias, and accuracy, see Practice E177.  
4.2 The procedures presented in this practice consist of three basic steps: planning the interlaboratory study, guiding the testing phase of the study, and analyzing the test result data.  
4.2.1 The planning phase includes forming the ILS task group, the study design, selection, and number of participating laborato...
SCOPE
1.1 This practice describes the techniques for planning, conducting, analyzing, and treating the results of an interlaboratory study (ILS) of a test method. The statistical techniques described in this practice provide adequate information for formulating the precision statement of a test method.  
1.2 This practice does not concern itself with the development of test methods but rather with gathering the information needed for a test method precision statement after the development stage has been successfully completed. The data obtained in the interlaboratory study may indicate, however, that further effort is needed to improve the test method.  
1.3 Since the primary purpose of this practice is the development of the information needed for a precision statement, the experimental design in this practice may not be optimum for evaluating materials, apparatus, or individual laboratories.  
1.4 Field of Application—This practice is concerned exclusively with test methods which yield a single numerical figure as the test result, although the single figure may be the outcome of a calculation from a set of measurements.  
1.4.1 This practice ...

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