FOCUS ON… THE NUMBER OF PANELISTS!

Do you regularly carry out consumer tests? So how do you choose the number of panelists you need to recruit? Probably taking into account the expected results, standards and your budget.

But do you know that it is possible to verify a posteriori what would have been the minimum number of consumers who would have guaranteed you the same results?

We invite you to discover our work on the subject at the next Pangborn in Providence, which can enable you to obtain real added value for the organization of your future consumer tests. Here is a preview of the abstract accepted:

“The number of subjects needed for sensory and consumer tests is an important and redundant problematic for most companies using sensory analysis routinely.

Indeed, the cost invested is directly impacted by the size of the panel, both for internal and outsourced studies.

Anyone can find norms and tables in literature proposing guidelines in terms of panel size: for example 100 consumers for a simple hedonic test (AFNOR), 30 subjects for a triangular difference test…

But these advices are finally empirical and “a priori” defined. It cannot really be adapted to the specific objectives and products of each company.

In this paper, we propose a systematic “a posteriori” approach based on resampling and enabling the optimization of panel sizes, according to specific products and methodologies.

Bootstrapping (Efron, 1979) is in that context a very useful statistical technique. Based on random sampling with replacement, it enables the simulation of thousands “realistic” panels from a single data set. By the way, the stability of the main results (significance of differences and/or similarities between products for example) can be studied while decreasing the size of a panel (e.g. 100, 80, 60…20, 10 subjects).

The paper will propose a methodology where the main criterion is defined as a best compromise between cost and information kept. Indices will be defined for the basic sensory and consumer tests (triangular and other difference tests, similarity tests, hedonic tests). But other indices for other sensory methods (profiling, free sorting task, JAR scales…) will also be proposed.

Examples from cosmetology and food industry fields will be presented, showing that this optimization could help companies getting their own expertise in terms of panel sizes.

Finally, the advantages and limits of this approach will be discussed, as well as the next development considered.”

If you don’t go to Pangborn this year, don’t hesitate to contact us for more information on the subject. It is also possible to adapt our method to all types of sensory tests. But this is another story… ! 😉

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