Nested Gauge R&R (Multiple Equipment, Multiple Appraisers, One Part)

The BIS.Net Team BIS.Net Team

There are many applications where an organization has multiple sets of measuring devices (equipment) opening the possibility of variation between the different measurement devices, which can introduce an additional source of error to measurements.

A nested gauge R&R is performed when appraisers cannot take measurements using all the measuring devices available for the study. For example, a measuring device may be kept in one laboratory, another in another and so on. Each laboratory has its own set of testers. Schematically, operators are nested in Equipment (Measuring device) as shown

Equipment 1 Equipment 2 Equipment 3 ....Equipment n
Appraiser A B C D E F G H I XYZ

For this layout a Nested Analysis of Variance is appropriate. Currently there are several restrictions

  • Each appraiser must perform at least 2 tests.
  • The number of appraisers per equipment must be greater than one.
  • The number of appraisers per equipment must be the same number
  • No appraiser will test more than one equipment
  • If different models are used, then do so only if the repeatability is known to be the same.

If one location has 3 appraisers, another 5 and another 2 then select two randomly appraisers for each

If a location has more than 1 equipment, test on a randomly selected measuring device. To test all devices in the location, perform a separate analysis, such as using the Gauge R&R Multiple Equipment, Multiple Devices, 1 Part module.

For this type of study each appraiser must test the same part at least twice with each measuring device.

Output for this type of analysis includes a Nested Analysis of Variance, a Dartboard, A Probability Plot and an Appraiser Reproducibility chart, such as shown below