E18.04 - Test Methods

SIGNIFICANCE AND USE
5.1 The test method is effective for the following test objectives:  
5.1.1 To determine whether a perceptible difference results or a perceptible difference does not result, for example, when a change is made in ingredients, processing, packaging, handling, or storage; or  
5.1.2 To select, train, and monitor assessors.  
5.2 The test method itself does not change whether the purpose of the test is to determine that the products are perceptibly different versus that the products are sufficiently similar to be used interchangeably. Only the selected values of α, β, and δ or Pd change. If the objective of the test is to determine if there is a perceptible difference between two products, then initially the products are assumed to be indistinguishable (for example, HO: δ or Pd = 0) and the data are examined to determine if the assumption can be rejected (that is, conclude that the products are perceptively different). If the objective is to determine if the two products are sufficiently similar to be used interchangeably, then initially the products are assumed to be meaningfully different (for example, HO: δ or Pd > the value chosen to represent a meaningful difference) and the data are examined to determine if the assumption can be rejected (that is, conclude that the samples are sufficiently similar to be used interchangeably).  
5.3 The tetrad method involves the evaluation of four samples. When the products being tested cause excessive sensory fatigue, carryover, or adaptation, methods that involve the evaluation of fewer samples (same-different, triangle test, etc.) may be preferred.
SCOPE
1.1 This test method covers a procedure for determining whether a perceptible sensory difference exists between samples of two products or to estimate the magnitude of the perceptible difference.  
1.2 This test method applies whether a difference may exist in a single sensory attribute or in several.  
1.3 This test method is applicable when the nature of the difference between the samples is unknown. The attribute(s) responsible for the difference are not identified.  
1.4 The tetrad test is more efficient statistically than the triangle test (Test Method E1885) or the duo-trio test (Test Method E2610).  
1.5 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.  
1.6 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.

SIGNIFICANCE AND USE
5.1 Acceptance and preference are the key measurements taken in consumer product testing as either a new product idea is developed into testable prototypes or existing products are evaluated for potential improvements, cost reductions, or other business reasons. Developing products that are preferred overall, or liked as well as, or better, on average, compared to a standard or a competitor, among a defined target consumer group, is usually the main goal of the product development process. Thus, it is necessary to test the consumer acceptability or the preference of a product or prototype compared to other prototypes or potential products, a standard product, or other products in the market. The researcher, with input from her/his stakeholders, has the responsibility to choose appropriate comparison products and scaling or test methods to evaluate them. In the case of a new-to-the-world product, there may or may not be a relevant product for comparison. In this case, a benchmark score or rating may be used to determine acceptability. A product or prototype that is acceptable to the target consumer is one that meets a minimum criterion for liking, and a product that is preferred over an existing product has the potential to be chosen more often than the less-preferred product by the consumer in the marketplace, when all other factors are equal.  
5.2 The external validity (the extent to which the results of a study can be generalized) of both acceptance and preference measures to manage decision risk at all stages of the development cycle is dependent on the ability of the researcher to generalize the results from the respondent sample to the target population at large. This depends both upon the sample of respondents and the way the test is constructed. Within the context of a single test, acceptance measures tell the relative hedonic status of the two samples, quantitatively, as well as where on the hedonic continuum each of the samples falls, that is, “disliked,”...
SCOPE
1.1 This guide covers acceptance and preference measures when each is used in an unbranded, two-sample, product test. Each measure, acceptance, and preference, may be used alone or together in a single test or separated by time. This guide covers how to establish a product’s hedonic or choice status based on sensory attributes alone, rather than brand, positioning, imagery, packaging, pricing, emotional-cultural responses, or other nonsensory aspects of the product. The most commonly used measures of acceptance and preference will be covered, that is, product liking overall as measured by the nine-point hedonic scale and preference measured by choice, either two-alternative forced choice or two-alternative with a “no preference” option.  
1.2 Three of the biggest challenges in measuring a product’s hedonic (overall liking or acceptability) or choice status (preference selection) are determining how many respondents and who to include in the respondent sample, setting up the questioning sequence, and interpreting the data to make product decisions.  
1.3 This guide covers:  
1.3.1 Definition of each type of measure,  
1.3.2 Discussion of the advantages and disadvantages of each,  
1.3.3 When to use each,  
1.3.4 Practical considerations in test execution,  
1.3.5 Risks associated with each,  
1.3.6 Relationship between the two when administered in the same test, and  
1.3.7 Recommended interpretations of results for product decisions.  
1.4 The intended audience for this guide is the sensory consumer professional or marketing research professional (“the researcher”) who is designing, executing, and interpreting data from product tests with acceptance or choice measures, or both.  
1.5 Only two-sample product tests will be covered in this guide. However, the issues and recommended practices raised in this guide often apply to multi-sample tests as well. Detailed coverage of execution tactics, optional types of s...

SIGNIFICANCE AND USE
5.1 Sensory thresholds are used to determine the potential of substances at low concentrations to impart odor, taste, skinfeel, etc. to some form of matter.  
5.2 Thresholds are used, for example, in setting limits for air pollution, in noise abatement, in water treatment, and in food systems.  
5.3 Thresholds are used to characterize and compare the sensitivity of individual or groups to given stimuli, for example, in medicine, in ethnic studies, and in the study of animal species.
SCOPE
1.1 This practice describes a rapid test for determining sensory thresholds of any substance in any medium.  
1.2 It prescribes an overall design of sample preparation and a procedure for calculating the results.  
1.3 The threshold may be characterized as being either (a) only detection  (awareness) that a very small amount of added substance is present but not necessarily recognizable, or (b) recognition  of the nature of the added substance.  
1.4 The medium may be a gas, such as air, a liquid, such as water or some beverage, or a solid form of matter. The medium may be odorless or tasteless, or may exhibit a characteristic odor or taste per se.  
1.5 This practice describes the use of a multiple forced-choice sample presentation method in an ascending concentration series, similar to the method of limits.  
1.6 Physical methods of sample presentation for threshold determination are not a part of this practice, and will depend on the physical state, size, shape, availability, and other properties of the samples.  
1.7 It is recognized that the degree of training received by a panel of assessors with a particular substance may have a profound influence on the threshold obtained with that substance  (1).2  
1.8 Thresholds determined by using one physical method of presentation are not necessarily equivalent to values obtained by another method.  
1.9 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.

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.

ABSTRACT
These practices are designed to outline two preferred procedures for referencing the odor intensities of any odorous material in the suprathreshold region on the ASTM Odor Intensity Referencing Scale. The method by which the reference odorant vapors are to be presented for evaluation by a panel of at least eight independent judgments is specified, but the manner by which the test sample is presented will depend on the nature of the sample, and is not defined herein. The methods, where a geometric progression scale with a ratio of 2 is recommended, are generally done by comparing the odor intensity of the sample to the odor intensities of a series of concentrations of the reference odorant 1-butanol (n-butanol). The two procedures differ in the method by which the diluted 1-butanol vapors are prepared. In Procedure A (dynamic scale method), a dynamic-dilution apparatus is used. This is equipped with a series of sniffing ports from which constant concentrations of 1-butanol emerge at constant volumetric flow rates in air. In Procedure B (static-scale method), a series of Erlenmeyer flasks containing known concentrations of 1-butanol in water is used.
SCOPE
1.1 This practice is designed to outline a means for referencing the odor intensities of a material in the suprathreshold region.  
1.2 The general objective is to reference the odor intensity rather than other odor properties of a sample.  
1.3 This practice is designed to reference the odor intensity on the ASTM Odor Intensity Referencing Scale of any odorous material. This is done by a comparison of the odor intensity of the sample to the odor intensities of a series of concentrations of a reference odorant, for example, 1-butanol (n-butanol).  
1.4 The method by which the reference odorant vapors are to be presented for evaluation by the assessors is specified. The manner by which the test sample is presented will depend on the nature of the sample, and is not defined herein.  
1.5 Test sample presentation should be consistent with good standard practice (1, 2)2 and should be explicitly documented in the test report.  
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.7 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. See Annex A1 for specific safety data.  
1.8 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.

SIGNIFICANCE AND USE
5.1 This test method is effective for the following test objectives:  
5.1.1 To determine whether a perceivable difference results or a perceivable difference does not result, for example, when a change is made in ingredients, processing, packaging, handling or storage; or  
5.1.2 To select, train and monitor assessors.  
5.2 This test method itself does not change whether the purpose of the triangle test is to determine that two products are perceivably different versus that the products are not perceivably different. Only the selected values of pd, α, and β change. If the objective of the test is to determine if there is a perceivable difference between two products, then the value selected for α is typically smaller than the value selected for β. If the objective is to determine if the two products are sufficiently similar to be used interchangeably, then the value selected for β is typically smaller than the value selected for α and the value of pd is selected to define “sufficiently similar.”
SCOPE
1.1 This test method covers a procedure for determining whether a perceptible sensory difference exists between samples of two products.  
1.2 This test method applies whether a difference may exist in a single sensory attribute or in several.  
1.3 This test method is applicable when the nature of the difference between the samples is unknown. It does not determine the size or the direction of the difference. The attribute(s) responsible for the difference are not identified.  
1.4 Compared to the duo-trio test, the triangle test can achieve an equivalent level of statistical significance with fewer assessors. For details on how the triangle test compares to other three-sample tests, see Refs (1) , (2), (3) and (4).2  
1.5 This test method is applicable only if the products are homogeneous. If two samples of the same product can often be distinguished, then another method, for example, descriptive analysis, may be more appropriate.  
1.6 This test method is applicable only when the products do not cause excessive sensory fatigue, carryover or adaptation.  
1.7 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.  
1.8 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.

SIGNIFICANCE AND USE
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.
SCOPE
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.

SIGNIFICANCE AND USE
5.1 The test method is effective for the following test objectives:  
5.1.1 To determine whether a perceivable difference results or a perceivable difference does not result, for example, when a change is made in ingredients, processing, packaging, handling or storage; or  
5.1.2 To select, train and monitor assessors.  
5.2 The test method itself does not change whether the purpose of the duo-trio test is to determine that two products are perceivably different versus that the products are not perceivably different. Only the selected values of pd, α, and β change. If the objective of the test is to determine if there is a perceivable difference between two products, then the value selected for α is typically smaller than the value selected for β. If the objective is to determine if the two products are sufficiently similar to be used interchangeably, then the value selected for β is typically smaller than the value selected for α and the value of pd is selected to define “sufficiently similar.”  
5.3 The test method may change based on the test objective or the assessors’ familiarity with the product. The balanced-reference technique (see 9.1.1) typically is used when neither product is more familiar than the other. The constant-reference technique (see 9.1.2) frequently is used when one product is a control/current product or is familiar to the assessors.
SCOPE
1.1 This test method covers a procedure for determining whether a perceptible sensory difference exists between samples of two products.  
1.2 This test method applies whether a difference may exist in a single sensory attribute or in several.  
1.3 This test method is applicable when the nature of the difference between the samples is unknown. It does not determine the size or the direction of the difference. The attribute(s) responsible for the difference are not identified.  
1.4 Compared to the triangle test, the duo-trio test is statistically less efficient, but easier to perform by the assessors. For details on how the duo-trio test compares to other three-sample tests, see Refs (1-4).2  
1.5 This test method is applicable only if the products are homogeneous. If two samples of the same product can often be distinguished, then another method, for example, descriptive analysis, may be more appropriate.  
1.6 This test method is applicable only when the products do not cause excessive sensory fatigue, carryover or adaptation.  
1.7 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.  
1.8 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.

SIGNIFICANCE AND USE
5.1 The paired preference test determines whether or not there is a preference for one product over another product among a specific target population. Knowledge of consumer segments, brand loyalties, the range of product offerings in the marketplace, and the decision risk must be understood when planning a paired preference test.  
5.2 The paired preference method is commonly used in tests with one or more of the following objectives: (1) to establish superiority in preference versus the competition for advertising claims support; (2) to establish the preference of a new product for launch versus a competitor's product; (3) to establish the preference of a reformulated product in a product improvement or product modification project (for example, process change or ingredient change); and (4) to establish the preference of a cost improved product versus the current formulation in a cost savings project. Selected values of Pmax, α, and β will change with all four types of test objectives. These should be selected prior to determination of N.  
5.2.1 Preference versus Competition or Launching a New Product versus Competition—Select a Pmax  to represent what you expect a reasonable preference split to be. The main risk to avoid is to wrongly claim your product is preferred over the competitors. Thus, low values of α are selected, for example, 0.05, 0.01, or 0.001. The desired outcome of this test is to reject the null hypothesis. The alternative hypothesis is one sided: A new or improved product (A) is preferred over the competitor’s product (B). The test is one-sided. The value of β will be determined by the sample size chosen and the size of the preference in the consumer segment selected for the test. Selection of the appropriate number of respondents is determined by Pmax, α, and β, as well as the market segment that must be included in the test (for issues specific to conducting a paired preference test for an advertising claim, refer to Guide E1958).  
5.2.2 C...
SCOPE
1.1 This document covers a procedure for determining preference between two products using either a two-alternative forced-choice task, or with the option of choosing no preference. Preference testing is a type of hedonic testing.  
1.2 A paired preference test determines whether there is a statistically significant preference between two products for a given population of respondents. The target population must be carefully considered.  
1.3 This method establishes preference in a single evaluation context. Replicated tests will not be covered within the scope of this document.  
1.4 Paired preference testing can address overall preference or preference for a specified sensory attribute.  
1.5 The method does not directly determine the magnitude of preference.  
1.6 This method does not address whether or not two samples are perceived as different. Refer to Test Method E2164 for directional difference test.  
1.7 A paired preference test is a simple task for respondents, and can be used with populations that have minimal reading or comprehension skills, or both.  
1.8 Preference is not an intrinsic attribute of the product, such as hue is, but is a subjective measure relating to respondents' affective or hedonic response. It differs from paired comparison testing which measures objective characteristics of the product. Preference results are always dependent on the population sampled.  
1.9 This standard does not purport to address all of the safety problems associated with its use, when testing includes hazardous materials, operations, or equipment. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and to 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 fo...

SIGNIFICANCE AND USE
4.1 Rating instruments or rating scales are commonly used in many areas such as sensory evaluation, marketing research, experimental psychology, survey research, and economics in which there is interest in quantifying perceptions such as liking, preference, level of purchase interest, intensity of an attribute, degree of difference, or level of agreement with statements. This guide is concerned with the scales that are used to record human responses to physical stimuli rather than measuring physical entities. Many types of rating scales already exist and have been used in the above fields. Specific rating scales each have their own properties, advantages, and disadvantages. Some rating scales are intended for specific applications, while others have broader applications. Some rating scales have been extensively studied and modeled and have well-established properties.  
4.2 Given the overwhelming number of scales available to practitioners when designing research, it is necessary for the researcher to have some knowledge about the scales that are available along with the many considerations that surround their use and applications. This guide will be useful to the sensory researcher who wants to use a scale as a measuring tool for their work. Selecting the right scale is a critical step towards meeting the research objective and making valid conclusions.
SCOPE
1.1 The objective of this guide is to provide information to be reviewed and considered by the sensory and consumer scientist who wants to select and use scales to measure responses from consumers or trained assessors. For ease of reading, the term sensory scientist is used throughout the guide when statements apply to the sensory and consumer scientists.  
1.2 This guide covers a brief definition of scales as well as some fundamental and practical challenges the sensory and consumer scientists should be aware of when using scales. It also provides a list and a description of the most commonly used scales in the field of sensory evaluation and consumer product research along with a classification framework for these scales.  
1.3 The scope of this guide is limited to the sensory and consumer science professional’s selection and use of rating scales when an assessor assigns one symbol/value to one stimulus, to their perception of a stimulus or an internal attitude/opinion. It does not cover:  
1.3.1 Details of analysis of data obtained from rating scales,  
1.3.2 Guidelines for questionnaire design including attribute selection,  
1.3.3 Fundamentals of measurement such as reliability and validity,  
1.3.4 Measurement models used to convert scale responses into measures of unobserved sensory or hedonic quantities,  
1.3.5 Tasks in which the assessor assigns a symbol/value to a group of stimuli,  
1.3.6 Rankings, and  
1.3.7 Multi-item scales.  
1.4 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.  
1.5 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.  
1.6 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.

SIGNIFICANCE AND USE
5.1 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.  
5.2 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.  
5.3 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 Ennis (1), MacRae (2), and O'Mahony and Odbert (3).2  
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.

SIGNIFICANCE AND USE
5.1 The test method is effective for the following test objectives:  
5.1.1 To determine whether a perceptible difference results or a perceptible difference does not result, for example, when a change is made in ingredients, processing, packaging, handling, or storage; or  
5.1.2 To select, train, and monitor assessors.  
5.2 The test method itself does not change whether the purpose of the test is to determine that the products are perceptibly different versus that the products are sufficiently similar to be used interchangeably. Only the selected values of α, β, and δ or Pd change. If the objective of the test is to determine if there is a perceptible difference between two products, then initially the products are assumed to be indistinguishable (for example, HO: δ or Pd = 0) and the data are examined to determine if the assumption can be rejected (that is, conclude that the products are perceptively different). If the objective is to determine if the two products are sufficiently similar to be used interchangeably, then initially the products are assumed to be meaningfully different (for example, HO: δ or Pd > the value chosen to represent a meaningful difference) and the data are examined to determine if the assumption can be rejected (that is, conclude that the samples are sufficiently similar to be used interchangeably).  
5.3 The tetrad method involves the evaluation of four samples. When the products being tested cause excessive sensory fatigue, carryover, or adaptation, methods that involve the evaluation of fewer samples (same-different, triangle test, etc.) may be preferred.
SCOPE
1.1 This test method covers a procedure for determining whether a perceptible sensory difference exists between samples of two products or to estimate the magnitude of the perceptible difference.  
1.2 This test method applies whether a difference may exist in a single sensory attribute or in several.  
1.3 This test method is applicable when the nature of the difference between the samples is unknown. The attribute(s) responsible for the difference are not identified.  
1.4 The tetrad test is more efficient statistically than the triangle test (Test Method E1885) or the duo-trio test (Test Method E2610).  
1.5 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.  
1.6 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.

SIGNIFICANCE AND USE
5.1 The test method is effective for the following test objectives:  
5.1.1 To determine whether a perceptible difference results or a perceptible difference does not result, for example, when a change is made in ingredients, processing, packaging, handling, or storage; or  
5.1.2 To select, train, and monitor assessors.  
5.2 The test method itself does not change whether the purpose of the test is to determine that the products are perceptibly different versus that the products are sufficiently similar to be used interchangeably. Only the selected values of α, β, and δ or Pd change. If the objective of the test is to determine if there is a perceptible difference between two products, then initially the products are assumed to be indistinguishable (for example, HO: δ or Pd = 0) and the data are examined to determine if the assumption can be rejected (that is, conclude that the products are perceptively different). If the objective is to determine if the two products are sufficiently similar to be used interchangeably, then initially the products are assumed to be meaningfully different (for example, HO: δ or Pd > the value chosen to represent a meaningful difference) and the data are examined to determine if the assumption can be rejected (that is, conclude that the samples are sufficiently similar to be used interchangeably).  
5.3 The tetrad method involves the evaluation of four samples. When the products being tested cause excessive sensory fatigue, carryover, or adaptation, methods that involve the evaluation of fewer samples (same-different, triangle test, etc.) may be preferred.
SCOPE
1.1 This test method covers a procedure for determining whether a perceptible sensory difference exists between samples of two products or to estimate the magnitude of the perceptible difference.  
1.2 This test method applies whether a difference may exist in a single sensory attribute or in several.  
1.3 This test method is applicable when the nature of the difference between the samples is unknown. The attribute(s) responsible for the difference are not identified.  
1.4 The tetrad test is more efficient statistically than the triangle test (Test Method E1885) or the duo-trio test (Test Method E2610).  
1.5 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.  
1.6 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.

SIGNIFICANCE AND USE
5.1 The test method is effective for the following test objectives:  
5.1.1 To determine whether a perceptible difference results or a perceptible difference does not result, for example, when a change is made in ingredients, processing, packaging, handling, or storage; or  
5.1.2 To select, train, and monitor assessors.  
5.2 The test method itself does not change whether the purpose of the test is to determine that two products are perceptibly different versus that the products are not perceptibly different. Only the selected values of δ, α, and β change. If the objective of the test is to determine if the two products are sufficiently similar to be used interchangeably, then the value selected for β is typically smaller than the value selected for α and the value of δ is selected to define “sufficiently similar.”
SCOPE
1.1 This test method covers a procedure for determining whether a perceptible sensory difference exists between samples of two products or to estimate the magnitude of the perceptible difference.  
1.2 This test method applies whether a difference may exist in a single sensory attribute or in several.  
1.3 This test method is applicable when the nature of the difference between the samples is unknown. The attribute(s) responsible for the difference are not identified.  
1.4 The tetrad test is more efficient statistically than the triangle test (Test Method E1885) or the duo-trio test (Test Method E2610).  
1.5 The tetrad method involves the evaluation of four samples. When the products being tested cause excessive sensory fatigue, carryover, or adaptation, methods that involve the evaluation of fewer samples (same-different, triangle test, etc.) may be preferred.  
1.6 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.

SIGNIFICANCE AND USE
5.1 The test method is effective for the following test objectives:  
5.1.1 To determine whether a perceptible difference results or a perceptible difference does not result, for example, when a change is made in ingredients, processing, packaging, handling, or storage; or  
5.1.2 To select, train, and monitor assessors.  
5.2 The test method itself does not change whether the purpose of the test is to determine that two products are perceptibly different versus that the products are not perceptibly different. Only the selected values of δ, α, and β change. If the objective of the test is to determine if the two products are sufficiently similar to be used interchangeably, then the value selected for β is typically smaller than the value selected for α and the value of δ is selected to define “sufficiently similar.”
SCOPE
1.1 This test method covers a procedure for determining whether a perceptible sensory difference exists between samples of two products or to estimate the magnitude of the perceptible difference.  
1.2 This test method applies whether a difference may exist in a single sensory attribute or in several.  
1.3 This test method is applicable when the nature of the difference between the samples is unknown. The attribute(s) responsible for the difference are not identified.  
1.4 The tetrad test is more efficient statistically than the triangle test (Test Method E1885) or the duo-trio test (Test Method E2610).  
1.5 The tetrad method involves the evaluation of four samples. When the products being tested cause excessive sensory fatigue, carryover, or adaptation, methods that involve the evaluation of fewer samples (same-different, triangle test, etc.) may be preferred.  
1.6 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.

SIGNIFICANCE AND USE
5.1 Acceptance and preference are the key measurements taken in consumer product testing as either a new product idea is developed into testable prototypes or existing products are evaluated for potential improvements, cost reductions, or other business reasons. Developing products that are preferred overall, or liked as well as, or better, on average, compared to a standard or a competitor, among a defined target consumer group, is usually the main goal of the product development process. Thus, it is necessary to test the consumer acceptability or the preference of a product or prototype compared to other prototypes or potential products, a standard product, or other products in the market. The researcher, with input from her/his stakeholders, has the responsibility to choose appropriate comparison products and scaling or test methods to evaluate them. In the case of a new-to-the-world product, there may or may not be a relevant product for comparison. In this case, a benchmark score or rating may be used to determine acceptability. A product or prototype that is acceptable to the target consumer is one that meets a minimum criterion for liking, and a product that is preferred over an existing product has the potential to be chosen more often than the less-preferred product by the consumer in the marketplace, when all other factors are equal.  
5.2 The external validity (the extent to which the results of a study can be generalized) of both acceptance and preference measures to manage decision risk at all stages of the development cycle is dependent on the ability of the researcher to generalize the results from the respondent sample to the target population at large. This depends both upon the sample of respondents and the way the test is constructed. Within the context of a single test, acceptance measures tell the relative hedonic status of the two samples, quantitatively, as well as where on the hedonic continuum each of the samples falls, that is, “disliked,”...
SCOPE
1.1 This guide covers acceptance and preference measures when each is used in an unbranded, two-sample, product test. Each measure, acceptance, and preference, may be used alone or together in a single test or separated by time. This guide covers how to establish a product’s hedonic or choice status based on sensory attributes alone, rather than brand, positioning, imagery, packaging, pricing, emotional-cultural responses, or other nonsensory aspects of the product. The most commonly used measures of acceptance and preference will be covered, that is, product liking overall as measured by the nine-point hedonic scale and preference measured by choice, either two-alternative forced choice or two-alternative with a “no preference” option.  
1.2 Three of the biggest challenges in measuring a product’s hedonic (overall liking or acceptability) or choice status (preference selection) are determining how many respondents and who to include in the respondent sample, setting up the questioning sequence, and interpreting the data to make product decisions.  
1.3 This guide covers:  
1.3.1 Definition of each type of measure,  
1.3.2 Discussion of the advantages and disadvantages of each,  
1.3.3 When to use each,  
1.3.4 Practical considerations in test execution,  
1.3.5 Risks associated with each,  
1.3.6 Relationship between the two when administered in the same test, and  
1.3.7 Recommended interpretations of results for product decisions.  
1.4 The intended audience for this guide is the sensory consumer professional or marketing research professional (“the researcher”) who is designing, executing, and interpreting data from product tests with acceptance or choice measures, or both.  
1.5 Only two-sample product tests will be covered in this guide. However, the issues and recommended practices raised in this guide often apply to multi-sample tests as well. Detailed coverage of execution tactics, optional types of s...

SIGNIFICANCE AND USE
5.1 Acceptance and preference are the key measurements taken in consumer product testing as either a new product idea is developed into testable prototypes or existing products are evaluated for potential improvements, cost reductions, or other business reasons. Developing products that are preferred overall, or liked as well as, or better, on average, compared to a standard or a competitor, among a defined target consumer group, is usually the main goal of the product development process. Thus, it is necessary to test the consumer acceptability or the preference of a product or prototype compared to other prototypes or potential products, a standard product, or other products in the market. The researcher, with input from her/his stakeholders, has the responsibility to choose appropriate comparison products and scaling or test methods to evaluate them. In the case of a new-to-the-world product, there may or may not be a relevant product for comparison. In this case, a benchmark score or rating may be used to determine acceptability. A product or prototype that is acceptable to the target consumer is one that meets a minimum criterion for liking, and a product that is preferred over an existing product has the potential to be chosen more often than the less-preferred product by the consumer in the marketplace, when all other factors are equal.  
5.2 The external validity (the extent to which the results of a study can be generalized) of both acceptance and preference measures to manage decision risk at all stages of the development cycle is dependent on the ability of the researcher to generalize the results from the respondent sample to the target population at large. This depends both upon the sample of respondents and the way the test is constructed. Within the context of a single test, acceptance measures tell the relative hedonic status of the two samples, quantitatively, as well as where on the hedonic continuum each of the samples falls, that is, “disliked,”...
SCOPE
1.1 This guide covers acceptance and preference measures when each is used in an unbranded, two-sample, product test. Each measure, acceptance, and preference, may be used alone or together in a single test or separated by time. This guide covers how to establish a product’s hedonic or choice status based on sensory attributes alone, rather than brand, positioning, imagery, packaging, pricing, emotional-cultural responses, or other nonsensory aspects of the product. The most commonly used measures of acceptance and preference will be covered, that is, product liking overall as measured by the nine-point hedonic scale and preference measured by choice, either two-alternative forced choice or two-alternative with a “no preference” option.  
1.2 Three of the biggest challenges in measuring a product’s hedonic (overall liking or acceptability) or choice status (preference selection) are determining how many respondents and who to include in the respondent sample, setting up the questioning sequence, and interpreting the data to make product decisions.  
1.3 This guide covers:  
1.3.1 Definition of each type of measure,  
1.3.2 Discussion of the advantages and disadvantages of each,  
1.3.3 When to use each,  
1.3.4 Practical considerations in test execution,  
1.3.5 Risks associated with each,  
1.3.6 Relationship between the two when administered in the same test, and  
1.3.7 Recommended interpretations of results for product decisions.  
1.4 The intended audience for this guide is the sensory consumer professional or marketing research professional (“the researcher”) who is designing, executing, and interpreting data from product tests with acceptance or choice measures, or both.  
1.5 Only two-sample product tests will be covered in this guide. However, the issues and recommended practices raised in this guide often apply to multi-sample tests as well. Detailed coverage of execution tactics, optional types of s...

SIGNIFICANCE AND USE
5.1 The paired preference test determines whether or not there is a preference for one product over another product among a specific target population. Knowledge of consumer segments, brand loyalties, the range of product offerings in the marketplace, and the decision risk must be understood when planning a paired preference test.  
5.2 The paired preference method is commonly used in tests with one or more of the following objectives: (1) to establish superiority in preference versus the competition for advertising claims support; (2) to establish the preference of a new product for launch versus a competitor's product; ( 3) to establish the preference of a reformulated product in a product improvement or product modification project (for example, process change or ingredient change); and (4) to establish the preference of a cost improved product versus the current formulation in a cost savings project. Selected values of Pmax, α, and β will change with all four types of test objectives. These should be selected prior to determination of N.  
5.2.1 Preference versus Competition or Launching a New Product versus Competition—Select a Pmax  to represent what you expect a reasonable preference split to be. The main risk to avoid is to wrongly claim your product is preferred over the competitors. Thus, low values of α are selected, for example, 0.05, 0.01, or 0.001. The desired outcome of this test is to reject the null hypothesis. The alternative hypothesis is one sided: A new or improved product (A) is preferred over the competitor’s product (B). The test is one-sided. The value of β will be determined by the sample size chosen and the size of the preference in the consumer segment selected for the test. Selection of the appropriate number of respondents is determined by Pmax, α, and β, as well as the market segment that must be included in the test (for issues specific to conducting a paired preference test for an advertising claim, refer to Guide E1958).  
5.2.2 ...
SCOPE
1.1 This document covers a procedure for determining preference between two products using either a two-alternative forced-choice task, or with the option of choosing no preference. Preference testing is a type of hedonic testing.  
1.2 A paired preference test determines whether there is a statistically significant preference between two products for a given population of respondents. The target population must be carefully considered.  
1.3 This method establishes preference in a single evaluation context. Replicated tests will not be covered within the scope of this document.  
1.4 Paired preference testing can address overall preference or preference for a specified sensory attribute.  
1.5 The method does not directly determine the magnitude of preference.  
1.6 This method does not address whether or not two samples are perceived as different. Refer to Test Method E2164 for directional difference test.  
1.7 A paired preference test is a simple task for respondents, and can be used with populations that have minimal reading or comprehension skills, or both.  
1.8 Preference is not an intrinsic attribute of the product, such as hue is, but is a subjective measure relating to respondents' affective or hedonic response. It differs from paired comparison testing which measures objective characteristics of the product. Preference results are always dependent on the population sampled.  
1.9 This standard does not purport to address all of the safety problems associated with its use, when testing includes hazardous materials, operations, or equipment. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
The test method is effective for the following test objectives:
To determine whether a perceivable difference results or a perceivable difference does not result, for example, when a change is made in ingredients, processing, packaging, handling or storage; or
To select, train and monitor assessors.
The test method itself does not change whether the purpose of the duo-trio test is to determine that two products are perceivably different versus that the products are not perceivably different. Only the selected values of pd, α, and β change. If the objective of the test is to determine if there is a perceivable difference between two products, then the value selected for α is typically smaller than the value selected for β. If the objective is to determine if the two products are sufficiently similar to be used interchangeably, then the value selected for β is typically smaller than the value selected for α and the value of pd is selected to define “sufficiently similar.”
The test method may change based on the test objective or the assessors’ familiarity with the product. The balanced-reference technique (see 9.1.1) typically is used when neither product is more familiar than the other. The constant-reference technique (see 9.1.2) frequently is used when one product is a control/current product or is familiar to the assessors.
SCOPE
1.1 This test method covers a procedure for determining whether a perceptible sensory difference exists between samples of two products.
1.2 This test method applies whether a difference may exist in a single sensory attribute or in several.
1.3 This test method is applicable when the nature of the difference between the samples is unknown. It does not determine the size or the direction of the difference. The attribute(s) responsible for the difference are not identified.
1.4 Compared to the triangle test, the duo-trio test is statistically less efficient, but easier to perform by the assessors. For details on how the duo-trio test compares to other three-sample tests, see Refs (1-4).  
1.5 This test method is applicable only if the products are homogeneous. If two samples of the same product can often be distinguished, then another method, for example, descriptive analysis, may be more appropriate.
1.6 This test method is applicable only when the products do not cause excessive sensory fatigue, carryover or adaptation.
1.7 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.

SIGNIFICANCE AND USE
Sensory thresholds are used to determine the potential of substances at low concentrations to impart odor, taste, skinfeel, etc. to some form of matter.
Thresholds are used, for example, in setting limits for air pollution, in noise abatement, in water treatment, and in food systems.
Thresholds are used to characterize and compare the sensitivity of individual or groups to given stimuli, for example, in medicine, in ethnic studies, and in the study of animal species.
SCOPE
1.1 This practice describes a rapid test for determining sensory thresholds of any substance in any medium.
1.2 It prescribes an overall design of sample preparation and a procedure for calculating the results.
1.3 The threshold may be characterized as being either (a) only detection  (awareness) that a very small amount of added substance is present but not necessarily recognizable, or (b) recognition  of the nature of the added substance.
1.4 The medium may be a gas, such as air, a liquid, such as water or some beverage, or a solid form of matter. The medium may be odorless or tasteless, or may exhibit a characteristic odor or taste per se.
1.5 This practice describes the use of a multiple forced-choice sample presentation method in an ascending concentration series, similar to the method of limits.
1.6 Physical methods of sample presentation for threshold determination are not a part of this practice, and will depend on the physical state, size, shape, availability, and other properties of the samples.
1.7 It is recognized that the degree of training received by a panel with a particular substance may have a profound influence on the threshold obtained with that substance (1).  
1.8 Thresholds determined by using one physical method of presentation are not necessarily equivalent to values obtained by another method.

SIGNIFICANCE AND USE
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.
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.
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).
The test provides a measure of the bias where judges perceive two same products to be different.
The test has the advantage of being a simple and intuitive task.
SCOPE
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 and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
This test method is effective for the following test objectives:
To determine whether a perceivable difference results or a perceivable difference does not result, for example, when a change is made in ingredients, processing, packaging, handling or storage; or
To select, train and monitor assessors.
This test method itself does not change whether the purpose of the triangle test is to determine that two products are perceivably different versus that the products are not perceivably different. Only the selected values of pd, α, and β change. If the objective of the test is to determine if there is a perceivable difference between two products, then the value selected for α is typically smaller than the value selected for β. If the objective is to determine if the two products are sufficiently similar to be used interchangeably, then the value selected for β is typically smaller than the value selected for α and the value of pd is selected to define “sufficiently similar.”
SCOPE
1.1 This test method covers a procedure for determining whether a perceptible sensory difference exists between samples of two products.
1.2 This test method applies whether a difference may exist in a single sensory attribute or in several.
1.3 This test method is applicable when the nature of the difference between the samples is unknown. It does not determine the size or the direction of the difference. The attribute(s) responsible for the difference are not identified.
1.4 Compared to the duo-trio test, the triangle test can achieve an equivalent level of statistical significance with fewer assessors. For details on how the triangle test compares to other three-sample tests, see Refs (1), (2), (3) and (4).  
1.5 This test method is applicable only if the products are homogeneous. If two samples of the same product can often be distinguished, then another method, for example, descriptive analysis, may be more appropriate.
1.6 This test method is applicable only when the products do not cause excessive sensory fatigue, carryover or adaptation.
1.7 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.

SIGNIFICANCE AND USE
Sensory thresholds are used to determine the potential of substances at low concentrations to impart odor, taste, skinfeel, etc. to some form of matter.
Thresholds are used, for example, in setting limits in air pollution, in noise abatement, in water treatment, and in food systems.
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 and health practices and determine the applicability of regulatory limitations prior to use.

ABSTRACT
These practices are designed to outline two preferred procedures for referencing the odor intensities of any odorous material in the suprathreshold region on the ASTM Odor Intensity Referencing Scale. The method by which the reference odorant vapors are to be presented for evaluation by a panel of at least eight independent judgments is specified, but the manner by which the test sample is presented will depend on the nature of the sample, and is not defined herein. The methods, where a geometric progression scale with a ratio of 2 is recommended, are generally done by comparing the odor intensity of the sample to the odor intensities of a series of concentrations of the reference odorant 1-butanol (n-butanol). The two procedures differ in the method by which the diluted 1-butanol vapors are prepared. In Procedure A (dynamic scale method), a dynamic-dilution apparatus is used. This is equipped with a series of sniffing ports from which constant concentrations of 1-butanol emerge at constant volumetric flow rates in air. In Procedure B (static-scale method), a series of Erlenmeyer flasks containing known concentrations of 1-butanol in water is used.
SCOPE
1.1 These practices are designed to outline a preferred means for referencing the odor intensities of a material in the suprathreshold region.
1.2 The general objective is to reference the odor intensity rather than other odor properties of a sample.
1.3 These practices are designed to reference the odor intensity on the ASTM Odor Intensity Referencing Scale of any odorous material. This is done by a comparison of the odor intensity of the sample to the odor intensities of a series of concentrations of the reference odorant, which is 1-butanol (n-butanol).
1.4 The method by which the reference odorant vapors are to be presented for evaluation by the panelists is specified. The manner by which the test sample is presented will depend on the nature of the sample, and is not defined herein.
1.5 Test sample presentation should be consistent with good standard practice (1) and should be explicitly documented in the test report.
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.7 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. See Annex A1 for specific safety data.

SIGNIFICANCE AND USE
The test method is effective for the following test objectives:
To determine whether a perceivable difference results or a perceivable difference does not result, for example, when a change is made in ingredients, processing, packaging, handling or storage; or
To select, train and monitor assessors.
The test method itself does not change whether the purpose of the duo-trio test is to determine that two products are perceivably different versus that the products are not perceivably different. Only the selected values of pd, α, and β change. If the objective of the test is to determine if there is a perceivable difference between two products, then the value selected for α is typically smaller than the value selected for β. If the objective is to determine if the two products are sufficiently similar to be used interchangeably, then the value selected for β is typically smaller than the value selected for α and the value of pd is selected to define “sufficiently similar.”
The test method may change based on the test objective or the assessors’ familiarity with the product. The balanced-reference technique (see 9.1.1) typically is used when neither product is more familiar than the other. The constant-reference technique (see 9.1.2) frequently is used when one product is a control/current product or is familiar to the assessors.
SCOPE
1.1 This test method covers a procedure for determining whether a perceptible sensory difference exists between samples of two products.
1.2 This test method applies whether a difference may exist in a single sensory attribute or in several.
1.3 This test method is applicable when the nature of the difference between the samples is unknown. It does not determine the size or the direction of the difference. The attribute(s) responsible for the difference are not identified.
1.4 Compared to the triangle test, the duo-trio test is statistically less efficient, but easier to perform by the assessors. For details on how the duo-trio test compares to other three-sample tests, see Refs (1-4).  
1.5 This test method is applicable only if the products are homogeneous. If two samples of the same product can often be distinguished, then another method, for example, descriptive analysis, may be more appropriate.
1.6 This test method is applicable only when the products do not cause excessive sensory fatigue, carryover or adaptation.
1.7 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.

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.
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 Ennis (1), MacRae (2), and O'Mahony and Odbert (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.

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.
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.

SIGNIFICANCE AND USE
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.
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.
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).
The test provides a measure of the bias where judges perceive two same products to be different.
The test has the advantage of being a simple and intuitive task.
SCOPE
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.
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 and health practices and determine the applicability of regulatory limitations prior to use.

ABSTRACT
These practices are designed to outline two preferred procedures for referencing the odor intensities of any odorous material in the suprathreshold region on the ASTM Odor Intensity Referencing Scale. The method by which the reference odorant vapors are to be presented for evaluation by a panel of at least eight independent judgments is specified, but the manner by which the test sample is presented will depend on the nature of the sample, and is not defined herein. The methods, where a geometric progression scale with a ratio of 2 is recommended, are generally done by comparing the odor intensity of the sample to the odor intensities of a series of concentrations of the reference odorant 1-butanol (n-butanol). The two procedures differ in the method by which the diluted 1-butanol vapors are prepared. In Procedure A (dynamic scale method), a dynamic-dilution apparatus is used. This is equipped with a series of sniffing ports from which constant concentrations of 1-butanol emerge at constant volumetric flow rates in air. In Procedure B (static-scale method), a series of Erlenmeyer flasks containing known concentrations of 1-butanol in water is used.
SCOPE
1.1 These practices are designed to outline a preferred means for referencing the odor intensities of a material in the suprathreshold region.
1.2 The general objective is to reference the odor intensity rather than other odor properties of a sample.
1.3 These practices are designed to reference the odor intensity on the ASTM Odor Intensity Referencing Scale of any odorous material. This is done by a comparison of the odor intensity of the sample to the odor intensities of a series of concentrations of the reference odorant, which is 1-butanol (n-butanol).
1.4 The method by which the reference odorant vapors are to be presented for evaluation by the panelists is specified. The manner by which the test sample is presented will depend on the nature of the sample, and is not defined herein.
1.5 Test sample presentation should be consistent with good standard practice () and should be explicitly documented in the test report.
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. See for specific safety data.

SIGNIFICANCE AND USE
This test method is effective for the following test objectives:
5.1.1 To determine whether a perceivable difference results or a perceivable difference does not result, for example, when a change is made in ingredients, processing, packaging, handling or storage; or
5.1.2 To select, train and monitor assessors.
This test method itself does not change whether the purpose of the triangle test is to determine that two products are perceivably different versus that the products are not perceivably different. Only the selected values of pd, α, and β change. If the objective of the test is to determine if there is a perceivable difference between two products, then the value selected for α is typically smaller than the value selected for β. If the objective is to determine if the two products are sufficiently similar to be used interchangeably, then the value selected for β is typically smaller than the value selected for α and the value of pd is selected to define “sufficiently similar.”
SCOPE
1.1 This test method covers a procedure for determining whether a perceptible sensory difference exists between samples of two products.
1.2 This test method applies whether a difference may exist in a single sensory attribute or in several.
1.3 This test method is applicable when the nature of the difference between the samples is unknown. It does not determine the size or the direction of the difference. The attribute(s) responsible for the difference are not identified.
1.4 Compared to the duo-trio test, the triangle test can achieve an equivalent level of statistical significance with fewer assessors. For details on how the triangle test compares to other three-sample tests, see Refs (1),  (2), (3) and (4).
1.5 This test method is applicable only if the products are homogeneous. If two samples of the same product can often be distinguished, then another method, for example, descriptive analysis, may be more appropriate.
1.6 This test method is applicable only when the products do not cause excessive sensory fatigue, carryover or adaptation.
1.7 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.

SIGNIFICANCE AND USE
Sensory thresholds are used to determine the potential of substances at low concentrations to impart odor, taste, skinfeel, etc. to some form of matter.
Thresholds are used, for example, in setting limits for air pollution, in noise abatement, in water treatment, and in food systems.
Thresholds are used to characterize and compare the sensitivity of individual or groups to given stimuli, for example, in medicine, in ethnic studies, and in the study of animal species.
SCOPE
1.1 This practice describes a rapid test for determining sensory thresholds of any substance in any medium.
1.2 It prescribes an overall design of sample preparation and a procedure for calculating the results.
1.3 The threshold may be characterized as being either (a) only detection  (awareness) that a very small amount of added substance is present but not necessarily recognizable, or (b) recognition of the nature of the added substance.
1.4 The medium may be a gas, such as air, a liquid, such as water or some beverage, or a solid form of matter. The medium may be odorless or tasteless, or may exhibit a characteristic odor or taste per se.
1.5 This practice describes the use of a multiple forced-choice sample presentation method in an ascending concentration series, similar to the method of limits.
1.6 Physical methods of sample presentation for threshold determination are not a part of this practice, and will depend on the physical state, size, shape, availability, and other properties of the samples.
1.7 It is recognized that the degree of training received by a panel with a particular substance may have a profound influence on the threshold obtained with that substance (1).
1.8 Thresholds determined by using one physical method of presentation are not necessarily equivalent to values obtained by another method.

SIGNIFICANCE AND USE
Sensory thresholds are used to determine the potential of substances at low concentrations to impart odor, taste, skinfeel, etc. to some form of matter.
Thresholds are used, for example, in setting limits in air pollution, in noise abatement, in water treatment, and in food systems.
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 and health practices and determine the applicability of regulatory limitations prior to use.

SCOPE
1.1 This document covers a procedure for determining preference between two products using a two-alternative forced-choice, which may or may not include the option of choosing no preference.
1.2 A paired preference test determines whether there is a statistically significant preference between two products for a given population of respondents. The target population must be carefully considered.
1.3 This method establishes preference in a single evaluation context. Replicated tests will not be covered within the scope of this document.
1.4 Paired preference testing can address overall preference or preference for a specified sensory attribute.
1.5 The method does not directly determine the magnitude of preference.
1.6 This method does not address whether or not two samples are perceived as different. See Test Method E 2164.
1.7 A paired preference test is a simple task for respondents, and can be used with populations that have minimal reading or comprehension skills, or both.
1.8 Preference is not an intrinsic attribute of the product, such as hue is, but is a subjective measure relating to respondents' affective or hedonic response. It differs from paired comparison testing which measures objective characteristics of the product. Preference results are always dependent on the population sampled.
1.9 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.

SCOPE
1.1 This test method covers a procedure for determining whether a perceptible sensory difference exists between samples of two products.
1.2 This test method applies whether a difference may exist in a single sensory attribute or in several.
1.3 This test method is applicable when the nature of the difference between the samples is unknown. It does not determine the size or the direction of the difference. The attribute(s) responsible for the difference are not identified.
1.4 Compared to the duo-trio test, the triangle test can achieve an equivalent level of statistical significance with fewer assessors. For details on how the triangle test compares to other three-sample tests, see Refs (1), (2), (3) and (4).
1.5 This test method is applicable only if the products are homogeneous. If two samples of the same product can often be distinguished, then another method, for example, descriptive analysis, may be more appropriate.
1.6 This test method is applicable only when the products do not cause excessive sensory fatigue, carryover or adaptation.
1.7 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.

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.

SCOPE
1.1 These practices are designed to outline a preferred means for referencing the odor intensities of a material in the suprathreshold region.
1.2 The general objective is to reference the odor intensity rather than other odor properties of a sample.  
1.3 These practices are designed to reference the odor intensity on the ASTM Odor Intensity Referencing Scale of any odorous material. This is done by a comparison of the odor intensity of the sample to the odor intensities of a series of concentrations of the reference odorant, which is 1-butanol ( -butanol).  
1.4 The method by which the reference odorant vapors are to be presented for evaluation by the panelists is specified. The manner by which the test sample is presented will depend on the nature of the sample, and is not defined herein.  
1.5 Test sample presentation should be consistent with good standard practice (1)  and should be explicitly documented in the test report.
1.6 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems 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.

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 problems, 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.

SCOPE
1.1 This practice describes a rapid test for determining sensory thresholds of any substance in any medium.  
1.2 It prescribes an overall design of sample preparation and a procedure for calculating the results.  
1.3 The threshold may be characterized as being either (a) only detection (awareness) that a very small amount of added substance is present but not necessarily recognizable, or (b) recognition of the nature of the added substance.  
1.4 The medium may be a gas, such as air, a liquid, such as water or some beverage, or a solid form of matter. The medium may be odorless or tasteless, or may exhibit a characteristic odor or taste per se.  
1.5 This practice describes the use of a multiple forced-choice sample presentation method in an ascending concentration series, similar to the method of limits.  
1.6 Physical methods of sample presentation for threshold determination are not a part of this practice, and will depend on the physical state, size, shape, availability, and other properties of the samples.  
1.7 It is recognized that the degree of training received by a panel with a particular substance may have a profound influence on the threshold obtained with that substance (1).  
1.8 Thresholds determined by using one physical method of presentation are not necessarily equivalent to values obtained by another method.

SCOPE
1.1 This test method covers a procedure for determining whether a perceptible sensory difference exists between samples of two products.