We are planning on doing a Gage R&R on Din cup 4 viscosity measurement. We usually use the method for our different products that vary in range from approx 30sec to 120sec. The specification range is normally +- 5, e.g 40-50 sec for one of our products. This product can come in at 60 or maybe 80 from production but is adjusted within spec (40-50 in this case). We plan to measure 5 different samples. In what range should we select samples? How will it affect the result if we pick samples in the range of 40-50 compared to 35-55?