A new approach to measuring Overall Liking with the Many-Facet Rasch Model

Abstract

The 9-point hedonic scale is the most common hedonic rating scale used to provide an assessment of overall liking. Studies have shown that consumer judgements of overall liking could be influenced by their ratings of the liking of flavour, texture, aroma or appearance. However, this is not directly taken into account when using the holistic variable of overall liking. A new approach is proposed for measuring overall liking that is firstly based on initially considering what sensory characteristics (attributes or modalities) defines the latent sensory construct of OVERALL LIKING. The aim of this study was to develop a single measure of Overall Liking that incorporates the relative importance of liking ratings from different sensory characteristics by applying a Many-Facet Rasch model to produce interval-scaled estimates of Overall Liking. A homogeneity test found significant differences (p < 0.01) between the Rasch means estimates of the cured 10 hams that were evaluated by a consumer panel (n = 90), with the two different definitions of the Rasch measure of Overall Liking. No significant differences were found when comparing Rasch measures with raw scores using an intrablock BIB ANOVA and Durbin test. The degree of Relevance, shown on a Many-Facet Wright map, indicated the extent which a variable contributed to the measure of Overall Liking. Of the 10 sensory attributes used for the Individual Attribute Measure, Hardness and Juiciness contributed the most, while Sweetness and Typical Flavour contributed the least. However, the modalities used in rating the Likings of Overall Flavour, Texture, Aroma and Appearance contributed almost to the same extent to Overall Liking in the Total Attribute Measure. The Wright Map also showed that the categories on the 9-point hedonic scale were unequally spaced and the distance between them became increasingly larger the further away from the central category of ‘Neither like nor dislike’.