# Gage R&R

Here is a process that I found online and adapted to a spreadsheet to calculate Gage R&R based on Average and Range

Average and Range TMV calculations

This is how its calculated:

This section describes the calculation method used to evaluate the test results from the Gauge R and R studies.

1. Test is conducted according to the required test protocol and data is collected.  Four data forms should be filled , two by each operator who should conduct two different tests.
2. Operator Range for each device will be calculated for each operator by subtracting the minimum measurement from the maximum measurement
3. Operator Average for each device will be calculated for each operator by adding the two measurements taken for the same device by each operator and dividing them by two (Number of trials).
4. The average operator range for each operator will be calculated by adding all the ranges for each device and dividing them by 10 (number of devices tested).
5. The average operator average measurement for each operator will be calculated by adding the average for each device and dividing them by 10 (number of devices tested)
6. Part average will be calculated by adding all the measurements for the same device and dividing them by 4 (number of trials by number of operators).
7. Part range will be calculated by subtracting the minimum measurement for each part to the maximum measurement for each device.
8. Operators average range (R) will be calculated by adding both average operators range and dividing them by two.
9. Operators range (X) will be calculated by subtracting the minimum average operator range from the maximum average operator range.
10. Range of parts (Rp) will be calculated by subtracting the minimum part average from the maximum part average.
11. K values will be used from table 4.3.1.1
12. Equipment variationEV) will be calculated by using this formula:

EV= R * K1

1. Appraiser variation (AV) will be calculated by using this formula: (n= number of devices, r =number of trials

AV=

1. Repeatability and (R&R) will be calculated by using this formula:

R&R=

1. Part variation (PV) will be calculated by using this formula:

PV= Rp * K3

1. Total Variation (TV) will be calculated by using this formula:

TV=

1. Percentage of variation will be calculated as follows:

%EV = EV / TV

%AV = AV / TV

% R&R = R&R/ TV

% PV = PV/ TV

• Repeatability—How much variability in the measurement system is caused by the measurement device.
• Reproducibility—How much variability in the measurement system is caused by differences between operators.

So, we want to see how much adding this two together can affect the “quality “ of the measurements, and this is what validates a test method.

Good luck!