Tetrad

Tetrad

Introduction

The Tetrad method is a testing procedure designed to understand the presence of a perceptible sensory distinction between two products. Panelists are given four samples, with two being identical and two being different. The panellists objective is to categorize the identical samples into two distinct groups.
This method is applicable whether the difference is related to a single sensory attribute or multiple attributes. It is suitable even when the specific nature of the difference is unknown and the attributes responsible for the distinction are not identified. The tetrad test is statistically more efficient than the triangle test or the duo-trio test. In cases where the tested products induce excessive sensory fatigue, carryover, or adaptation, methods that involve evaluating fewer samples (such as the same-different test or the triangle test) may be preferable.

Template Description

The template starts with a screen, which can be used for welcoming panellists or asking additional questions prior to the tetrad test. In the design section, the first screen has instructions specific to the tetrad task, followed by a question where participants are presented with four blinded-coded samples and are asked to sort the samples according to their similarity. The question type included is a "Binning with sample". In the settings of this question, you have the option to customize the names of the groups. The template initially suggests the default names as Group A and Group B. Once the grouping task is completed, panelists have the opportunity to add comments.
On the end screen, the template incorporates a thank-you message, providing an opportunity for you to personalize a final message for the panellists. 
Within the design settings, you can examine how each panellist will receive the sample, with each set corresponding to a specific order of presentation for an individual panellist. The test employs a block design, presenting four samples simultaneously to the panelists. The order of presentation is randomized across all sets/panellists. 
Moreover, you have the option to display the results directly to each panelist. If you wish to implement this within your questionnaire, please consult the following article for guidance: https://support.eyequestion.nl/portal/en/kb/articles/how-to-display-feedback-of-triangle-and-tetrad-test

Raw Data Representation

The raw data will be displayed, with each row corresponding to an individual judge and the pair of products they were presented with. The data will be stored to indicate whether the panellists correctly placed the identical samples within the same group or not. If the answer is incorrect, the data will be recorded as a 0, whereas if the panellists answer correctly, the data will be recorded as a 1. The Q1_info column provides additional information on how panellists grouped the products.

Analysis

Once data has been gathered, you can access EyeOpenR and navigate to the Discrimination methods. Choose the analysis “Tetrad” to examine your results. Additional details about this analysis can be found in the following article:

References

ASTM E3009-15 Tetrad

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