Author(s)

Jürgen Blaak¹, Daniela Keller², Isabel Simon¹, Marina Schleißinger¹, Nanna Y. Schürer³, Peter Staib^1*

¹Research & Development and Regulatory Affairs, Kneipp GmbH, Würzburg, Germany.
²Statistik & Beratung Daniela Keller, Kürnach, Germany.
³Department of Dermatology, Environmental Medicine and Health Theory, University of Osnabrück, Germany.

Subjective evaluations are nowadays applied more commonly in cosmetic product assessment. They are used in quality control, product development steps and efficacy studies for claim support. Several studies have been published to determine the adequate number of panelists, but recommendations and guidelines dealing with this topic are rare in the cosmetic sector. The aim of the present pilot study was to recommend a suitable study plan and define the adequate consumer panel size for cosmetic consumer assessment. A questionnaire-based product evaluation study, with three different cosmetic products, was organized as a consumer test using a seven-point scale. As a last step, a specific statistical calculation was performed to define the minimum sample size. It showed that the minimum sample size, besides the obvious statistical parameters of standard deviation and confidence interval, also depends on age and gender of the panelists and product assessment item. Utilizing a CI of 95% a minimum of 60 panelists seems to be sufficient for home-use-test (HUT) with a given seven-point scale. A minimum of 101 panelists are shown to be sufficient utilizing a CI of 99%.

Claim Substantiation, Consumer Panel Size, Product Evaluation, Sample Size Calculation

Blaak, J. , Keller, D. , Simon, I. , Schleißinger, M. , Schürer, N. and Staib, P. (2018) Consumer Panel Size in Sensory Cosmetic Product Evaluation: A Pilot Study from a Statistical Point of View. Journal of Cosmetics, Dermatological Sciences and Applications, 8, 97-109. doi: 10.4236/jcdsa.2018.83012.