Slipperiness of a floor is a major cause of slip and fall accidents.   The measurement of floor slipperiness is determined by the coefficient of friction (COF).   The magnitude of COF values differ across machine types (e.g. BOT, English XL, Brungraber) using different operating principles.   As a result, comparison of COF across different floor surfaces is typically done using a single machine type.   The current study seeks to answer three important research questions regarding the measurement of COF: (1) Do different machines provide the same interpretation about slipperiness of a floor tile, irrespective of differences in magnitude, (2) Does the experience of the machine operator affect the COF reading and (3) Does the variability of the COF reading varies across machine type.   The above research questions are investigated using experimental data from two lab experiments.   Each lab experiment is based on a factorial design and involves the measurement of COF using three different machine types on three floor tile-types by four operators in the first experiment and two operators in the second experiment.   Analysis of variance (ANOVA), F-tests and Levene’s tests were conducted on the experimental data.   It was observed from the statistical analyses that the three machines ranked the three tiles differently based on the COF, providing conflicting ideas about the slipperiness of those floor tile-types.   The effect of operators was not found to be statistically significant, while the variability of the machines and tile-type interaction was statistically significant.   The two lab experiments’ results were consistent with some previously collected data from the field.