Siegmund GP, Blanchette MG, Brault JR, Chimich DD, Elkin BS (2020). Quantifying the uncertainty in tribometer measurements on walkway surfaces. Ergonomics. doi: 10.1080/00140139.2020.1797182.
Properly estimating and reporting the uncertainty of walkway surface friction is key to ensuring pedestrian safety. Here we quantified the amount and sources of uncertainty in friction measurements by having four users of four units of each of two walkway tribometer models (Slip-Test Mark IIIB, English XL) perform 12 measurements on four samples of four different surfaces that ranged from slippery to slip resistant.
We found that 51 to 82% of the total variance in the measurements was explained by the user, unit, sample and a user × unit interaction, which means that the variance a single user calculates from their own data does not capture most of the uncertainty in their measurements. Based on these data, the minimum uncertainty associated with the mean of a user’s measurements is ±0.064 (Mark IIIB) and ±0.072 (XL) to be 95% confident that their mean captures a surface’s available friction.