# Sensory Panel Performance Evaluation--Comprehensive Review of Practical Approaches
## 4 Methods, Models and Frameworks in Sensory Panel Evaluation
### Indicators and Effects of Individual Assessor and Panel Performance  
There are three classic performance indicators for individual assessors and for the panel: discrimination, agreement and repeatability. The reproducibility indicator is added to the panel performance standard [44]:  
* Discrimination of an assessor/panel: ability of the assessor/panel to exhibit significant differences among products, (assessor: ANOVA one fixed factor (product); panel: ANOVA two fixed factors (product, assessors) and interaction). * Agreement of an assessor/panel: agreement ability of different panels or assessors to exhibit the same product differences when assigning scores on a given attribute to the same set of products, (assessor: distance and correlation to panel median; panel: significant difference among assessors). * Repeatability of an assessor: the degree of homogeneity between replicated assessments of the same product. Repeatability of a panel: the agreement in assessments of the same set of products under similar test conditions by the same assessors at different time points (assessor: ANOVA one fixed factor (product); panel: ANOVA two fixed factors (product, assessors) + interaction). Reproducibility of the panel: the agreement in assessments of the same set of products under similar test conditions by different assessors (panel) at different time points (between-sessions in three-way ANOVA). Discrimination is, in fact, the ability to distinguish between products, and is, therefore, usually characterized by discriminatory and/or separating ability. Non-conform discrimination is possible due to the use of inappropriate assessor selection methods, sensory fatigue or inadequate sensory memory or concentration. The repeatability of an assessor/panel shows to what extent an assessor/panel is able to perform the same assessment to the same product at another test session. Measurements of repeatability of the assessors are typically performed on two consecutive days, but it is also feasible to implement those tests on the same date with two sessions. Repeatability is affected by the altered sensitivity, the adapted cognitive processing of sensory stimuli, the mental conditions, the health status, the motivation, and the different test dates. If an assessor/panel does not have sufficient repeatability, targeted training is necessary or the result should be excluded from further evaluations. Inadequate repeatability can be influenced by several factors: firstly, from the natural heterogeneity of the samples (shape, size, color of vegetables and fruits); secondly, from the applied processing technology (position of the baked goods on the baking tray, salting homogeneity of French fries, the composition of complex meat products, etc. ); third, they result from the differences in the preparation and presentation of the sensory test samples. It is recommended that one person should always prepare sensory test samples for better homogeneity. The reproducibility of the panels is determined by the sensory abilities of the members, their proficiency in the test method and their knowledge of the product and its intensities [13; 44; 46]. All performance characteristics can be affected by different scale usage, which can result in distorting effects. Based on the patterns of the scale evaluation, level effect, range effect and variability effect are distinguished (Figure 1). The level effect shows the location of the average points on the intensity scale, the range effect is the exact variance and the variability effect is characterized by the extent of the values. The reasons for the different use of the scale are worth exploring because this allows the panel leader to define individualized tests, thus improving the reliability of the assessor and the entire panel. Correcting differences in scale use reduces the interaction effect [13; 14]. During sensory evaluations, differences in the range, standard deviation and mean of the points are due to the different use of the scale (level, range, variability).