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,” “neutral,” or “liked.” In contrast, preference measures tell the relative choice status of two samples within a specific respondent group. Results from these measures can and will vary from test to test depending on the number and type of respondents serving in each test, the size and nature of the sensory differences between the two samples, the method of executing the test, and any error present in the test. The identification, control, measurement, and tracking of variables that may influence results across tests (for example, production location, sample age, and storage conditions) are the responsibility of the researcher.
5.3 While measures of acceptance and preference are both subjective responses to products, and can be somewhat related, they provide different information. A product may be “acceptable” but still not be preferred by the consumer over other alternatives, and conversely, a product may be preferred over another but still not be acceptable to the consumer. These two terms, therefore, should not be used interchangeably. When a bipolar hedonic scale with multipoint options is used, the researcher should specifically refer to “liking,” “acceptance,” or “hedonic ratings.” When preference measures are used, the researcher should refer to, “preference,” “product selection,” or “choice.” Research professionals themselves should be precise in their usage of the terms “acceptance” and “liking,” to refer only to scaling of liking. These researchers should use the terms “preference” and “choice” to refer to two (“Prefer A” or “Prefer B”) or three-choice (“Prefer A” or “Prefer B” or “No Preference”) response options given in a preference test. In addition to having different meanings, the two measures also do not always provide similar results. This guide will cover the similarities and differences in information each provides, some guidelines around implementation, and interpretation of findings. This guide will thus give users an understanding of the issues at hand when planning, designing, implementing, and interpreting results from acceptance and preference tests with consumers.
5.4 While both measures are commonly used to provide information for product development decisions and evaluating a product’s competitive status, it is important to remember that pricing, positioning, competitive options, product availability, and other marketplace factors also impact a product’s success.
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 scales, various approaches to data analysis, and extensive discussions of the reliability and validity of these measures are all outside of the scope of this guide.
1.6 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.
1.7 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.