A test-retest study is performed to a coordinate measuring machine (CMM) using a working standard of 100.00 ± 0.001 mm (95% confidence). The length of the standard is measured 30 rimes. The mean and standard deviation of the measurements are x = 107.883 mm and 5 = 2.497 mm. All of the measurements are made are the same location on the standard and are taken by the same technician, who mounts and dismounts the unit for each measurement.

The precision of the CMM is estimated to be