The variation (error) contributed by both Gage Repeatability and Reproducibility:
EV is the Equipment Variation, or Repeatability
AV is the Appraiser Variation, or Reproducibility
% R&R is calculated using the Total Variation (TV):
% R&R may also be calculated using the Part Tolerance:
where USL is the Upper Specification Limit and LSL is the Lower Specification Limit
The %R&R relative to process variation is interpreted differently than the %R&R to the allowable tolerance.
See also: Gage R&R Analysis