Study of consistency of expert evaluations of wine sensory characteristics by positional analysis

Individual characteristics inherent in the expert, as well as their physical and psycho-emotional state subject to the influence of random, uncontrollable factors, contribute to subjectivity in the sensory evaluation of wines. With great variability of opinions, the final results of sensory evaluation may become doubtful. The presence of a random component in the sensory evaluation justifies the use of statistical methods for analyzing the consistency of expert evaluations. Along with Spearman's correlation coefficients and Kendall matching, Cronbach alpha criterion was used to assess the consistency of expert opinions. The advantages of positional analysis have been discussed – Cronbach's alpha criterion is calculated not by the rank of expert points, but by the initial point scale considering its variability; it allows to evaluate the contribution of each expert to the consistency of expert evaluations, as well as the reliability of the total scale of points set for each wine sample. Based on the data analysis from sensory evaluation of the quality of dry red and white wines of Russian production, the results of the consistency study of expert evaluations as well as the reliability of the total score scale have been presented. What is more, analysis of the “loyalty” of experts in evaluating the quality of wines has been performed.