Paired comparison test

Comparison of Sweetness between Trehalose Derivatives and the Corresponding Monosaccharide Analogs by Paired Comparison Test d... 

If the 3- and 4-hydroxyl groups constitute the Shallenberger AH,B unit, it is possible that a disaccharide (such as a,a-trehalose) and methyl a-D-glucopyranoside may possess the same molar sweetness. By a ranking procedure, and using trained panelists in a Paired Comparison Test, it was, indeed, found that isomolar solutions of these two sugars are equi-... 

Comparison of Sweetness between Reducing Disaccharides and Monosaccharides" by Paired Comparison Test on Sugar Solutions... 

In paired comparison tests two different samples are presented and one asks which of the two samples has most of the sensory property of interest, e.g. which of two products has the sweetest taste (Fig. 38.3). The pairs are presented in random order to each assessor and preferably tested twice, reversing the presentation order on the second tasting session. Fairly large numbers (>30) of test subjects are required. If there are more than two samples to be tested, one may compare all possible pairs ( round robin ). Since the number of possible pairs grows rapidly with the number of different products this is only practical for sets of three to six products. By combining the information of all paired comparisons for all panellists one may determine a rank order of the products and determine significant differences. For example, in a paired comparison one compares three food products (A) the usual freeze-dried form, (B) a new freeze-dried product, (C) the new product, not freeze-dried. Each of the three pairs are tested twice by 13 panellists in two different presentation orders, A-B, B-A, A-C, C-A, B-C, C-B. The results are given in Table 38.3. 

The results of such multiple paired comparison tests are usually analyzed with Friedman s rank sum test [4] or with more sophisticated methods, e.g. the one using the Bradley-Terry model [5]. A good introduction to the theory and applications of paired comparison tests is David [6]. Since Friedman s rank sum test is based on less restrictive, ordering assumptions it is a robust alternative to two-way analysis of variance which rests upon the normality assumption. For each panellist (and presentation) the three products are scored, i.e. a product gets a score 1,2 or 3, when it is preferred twice, once or not at all, respectively. The rank scores are summed for each product i. One then tests the hypothesis that this result could be obtained under the null hypothesis that there is no difference between the three products and that the ranks were assigned randomly. Friedman s test statistic for this reads... 

Fig. 38.3. Paired comparison test two different products are presented and the assessor has to indicated the one that has most of a specified attribute.

Paint technologies, 18 54-55, 56 Paint viscosity, measuring, 18 69 Paired comparison test, 11 512 Paired synthesis, of phthalide and 4.4-butylbenzaldehyde, 9 680-681 PAI resins, properties of, 10 215t Pair production process, 21 313 Palatinit, 12 44... 

Sensory Analysis. A paired comparison test was run to determine if the difference in oil droplet size in the emulsion changed the perceived intensity of the orange flavor. The coarsest emulsion (3.87 pM) and the Microfluidized sample (0.90 pM) from the third set of spray dried samples were compared. The solutions were prepared using 200 ppm flavor in a 10% (w/v) sucrose solution with 0.30% of a 50% citric acid solution added. The amount of each powder required to attain 200 ppm orange oil was calculated on the basis of percent oil in each powder (determined by Clevenger analysis). A pair of samples at approximately 10 C was given to each of 24 untrained panelists. The samples were coded with random numbers. Half the panelists were asked to taste the coarsest sample first while while the other half tasted the Microfluidized sample first. This was done to determine whether or not adaptation was a factor. The panelists were asked to indicate which sample had the most intense orange flavor. 

Sensory Evaluation. The organoleptic evaluation of the samples was conducted by a paired comparison test. The expert panel consisted of six to eight members.The encapsulated samples (stored at 45 C) were evaluated against the control samples at O.IJIJ (w/w) in spring water. 

Sensory Evaluation. Results on the sensory evaluation of the three encapsulated powders showed that all three powders developed oxidized flavor even at first sampling time (3 days). Since an expert trained panel was used, the recognition threshold of members for oxidized flavor was far below the expected value. In addition, since oven stored samples were evaluated against freezer stored samples in the pair comparison test, panelists could not characterize the degree of difference in oxidized flavor between various powders. It is therefore suggested that lower storage... 

DUO tests are particularly suitable for this, i.e. tests in which pairs of samples are compared. These are tests such as the Paired Comparison Test (DIN Standard 10 954 [5], ISO Standard 5495 [6]) and the Comparison Test which does not involve a direct question about the difference. [Although it is called a Comparison Test in English, it actually deals with differences]... 

ISO 5495 Sensory Analysis - Methodology - Paired Comparison Test (1983)... 

Optical brightener. Because of the screening effect of the active, softened fibers may reflect less light and be somewhat less bright. To overcome the problem, manufacturers add an optical brightener to some products. A benefit can indeed be displayed in the laboratory by fluorescence and pair comparison tests users, who do not perform pair comparisons, hardly detect the difference. The benefit on colored items is more obvious and the consumer usually perceives the color revival. Selecting a candidate requires a preliminary assessment of possible hue changes. 

Analytical methods can be sub-divided into difference tests and descriptive analysis. Difference tests such as triangle and paired comparison tests are designed to identify differences between samples. In a triangle test, the assessor is given three samples, two of which are the same, and asked to identify which sample is different. In a paired comparison test, the assessor is asked to identify whether there is a difference in a particular sensory characteristic between a pair of samples. Descriptive analysis, in which the sensory characteristics of a sample are described and scored on a scale, is probably the most important analytical method. 

The brewer and his customer make a subjective assessment of beer flavour each time they taste but for a more objective appraisal it is usually desirable to submit the beer, with suitable controls, to a taste panel. Taste panels may be used to (/) select qualified judges, (//) correlate sensory with chemical and physical measurements, (Hi) study processing effects, maintain quality, evaluate raw material selection, establish storage stability, and reduce costs, (fv) evaluate quality, and (v) determine consumer reaction [Ij. The types of test used include (/) difference tests, (ii) rank order, (Hi) scoring tests, (iv) descriptive tests, (v) hedonic scaling, and (v/) acceptance and preference tests [1]. Difference tests are most commonly used in the brewing industry, the results of which are readily analysed by statistics. Several forms of difference test are used. The A-not-A form of test is perhaps the simplest. Assessors are first familiarized with a standard A and then presented, in a random manner, either with A again or with the comparative sample B. In the paired-comparison test two samples are presented simultaneously (AA, AB, BA, or BB) and assessors report either there is a difference or there is no difference . 

Previous research on the perception threshold has shown that the elderly were able to perform 2-AFC or 3-AFC type tasks (Mojet et al., 2001) for a review see Methven et al. (2012). As a consequence, it may be relevant to conduct discriminative tasks with elderly people so as to, for example, check if any improvement brought to the product has actually been perceived by this population or not. Yet, as attentional capacities decline with age, we recommend choosing duo-trio tests, or paired comparison tests, rather than a triangle test or tetrad. Indeed, the latter require comparing simultaneously more samples than the former, and are therefore more costly from a cognitive point of view. 

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