Subjective evaluations of slipperiness of floor coverings

INRS has developed a psychophysical evaluation method based on perceived slipperiness while walking, derived from Thurstone's method of "pairwise comparison".
This document presents the protocol for these psychophysical trials with the operating procedure, the test conditions, the choice of the test evaluators and the test bench that was specially developed.
The tests were performed in two configurations: wearing shoes and with oil, and barefoot with water to which lauryl sulphate was added.
The statistical analysis showed that regardless of the pollutant, all 12 evaluators showed strong matches in their comparisons of the 15 floor coverings. The Spearman's coefficients of correlation and the Kendall's coefficients of concordance had very high values. They were all greater than o.8.
The analysis also showed lack of distinctions between certain pairs of coverings, and such lack of distinctions will need to be taken into account when comparing the metrology methods.
The psychophysical method achieves the objective that was to classify in order of perceived slipperiness the 15 floor coverings. It is sufficiently robust to be used as a reference method.