Browsing by Author "Sriwattana S"

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    Sensitivity reliability and neutral tendency of hedonic ratings as affected by scale types and lengths and overall product impression
    (26/06/2012) Jirangrat W; Wang J; Corredor JAH; Sriwattana S; Prinyawiwatkul W
    Several scales are available for measuring degrees of liking/disliking. Information on characteristics of hedonic ratings as affected by scale types/lengths and overall product impression is limited. Therefore, we compared discriminatory power, sensitivity, reliablity, and neutral tendency of hedonic ratings collected from 9-point categorical (CAT), line (LIN), and labeled affective magnitude (LAM) scales (100-mm compared 300-mm length). Three grape juices (classified as A=liked, B=moderate, C=disliked) were arranged in 4 sets (AB-AC, BA-CA, AC-AB, or CA-BA; the left sample served first). Each panelist (N=60) evaluated color (OC), taste (OT), and overall-liking (OL) of 1 set (of 4 possible random serving sets) in all 6 independent sessions (3 scale types x 2 lengths). For OL determined on a 100-mm scale, the order of discriminatory power (determined by the MIXED procedure) was CAT>LAM>LIN. The 300-mm LAM scale was consistently more discriminatory than the 100-mm LAM scale for all attributes. For sensitivity (the number of significantly different pairs), CAT exhibited the highest sensitivity, considering simultaneously all products (A, B, C) categories. Regardless of attributes, product categories, and scale types, ratings tended to be lower with the 300-mm scale. For reliability (consistency of responses towards OC/OT/OL) of different scale/length types, Cronbach’s alpha values were 0.78-0.92, with slightly higher (0.89-0.92) values toward the disliked sample. Another reliability index (consistency of responses between 2 identical test samples) across different scale/length types was exhibited by Pearson’s correlation coefficients (r=0.32-0.75), with higher values toward the LAM scale; OC (a less complicated attribute) was less affected (higher r values). Product categories and scale types affected neutral tendency of responses, with moderate and disliked products being more affected when evaluated on LAM scales. This study demonstrated characteristics of hedonic scales as affected by scale lengths and overall product impression. Using proper scales to assess liking/disliking would help increase power of the experiment.
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    Variations in heading ratings characterized by scale polarity scale types and attributes
    (26/06/2012) Jirangrat W; Ordonez K; Wang J; Corredor JAH; Sriwattana S; Prinyawiwatkul W
    The negative side of the 9-point hedonic scale is not fully understood. When used to evaluate negative attributes (for example, bitterness), this hedonic scale may yield poor results. We evaluated hedonic ratings as affected by scale types [9-point-categorical (CAT), line (LIN) and labeled-affective-magnitude (LAM)] and polarity (uni- compared to bi-polar), and attributes (positive compared to negative). We compared sensitivity and confounding effects [contrast+panelist effects=CP] of positive- and negative-attribute ratings among 3 scales, and compared effects of uni- (negative-side only) compared to bi-polar scales on negative-attribute ratings. Grape juices (classified as A=Liked, B=Moderate, C=Disliked) arranged in 4 sets (AB-AC, BA-CA, AC-AB, or CA-BA; the left sample served first) were evaluated (N=60 consumers) for overall-liking using 3 scales. Low-sodium chicken broths (classified as M=Mild- and S=Strong-bitterness) arranged in 2 sets (MS or SM) were evaluated (N=216) for bitterness using 3 scales. Balanced/randomized presentation was practiced. With bi-polar scales: 1) consumers better differentiated negative-attribute ratings; 2) CP was higher for positive- than negative-attribute ratings [5.47 compared to 0.11, 12.41 compared to 0.09, and 82.66 compared to 0.23, respectively, for CAT, LIN, and LAM; 3) LAM was more affected by CP. With negative-attribute ratings, CP of LAM was higher for uni- than for bi-polar scales. CP was more pronounced for liked- than disliked-samples, resulting in higher score fluctuation. CAT was more affected by contrast effects whereas LIN and LAM were more affected by panelist effects. Polarity effects were obvious for the mild-bitterness sample, showing significantly different results between uni- compared to bi-polar scales [3.91 compared to 6.39, 4.28 compared to 6.49, and 41.05 compared to 63.24, respectively, for CAT, LIN, and LAM]; all ratings from bi-polar scales were not on the negative-side. For the strong-bitterness sample, uni- and bi-polar ratings were on the negative side, with LAM having more consistent pattern. This study revealed some drawbacks of hedonic scales induced by scale polarity/types and attributes.