The machine is easy to explain to nontechnical people like Juries. ASTM protocol shows that it may be used on wet surfaces. The device does not claim to be statistically accurate at COF readings above .8 and below .2. In practice, however, readings in these ranges are not important. The COF measurement is computed by dividing the horizontal force by the vertical force.
Critics say that measurements made with a device pulled by hand produce wide variations.
ASTM-listed measurements of precision show that one can expect standard deviation reading of .05 on wet surfaces. However, deviations of .05 to .07 are significant improvements over many test devices. This machine was designed to be inexpensive and shop-built. As a test protocol, it is accepted by American courts for testing both roadway surfaces and tile floors. This is a laboratory machine sponsored for a test protocol by the association of floor-care product manufacturers in 1975.