Specifying nesting for Gage R&R Study (Expanded)main topic
Specifying nesting for Gage R&R Study (Expanded)Specify nested factors using ( ). Terms in parentheses are always factors in the model and are listed with blanks between them.
When B is nested within A, type B(A).
When C is nested within both A and B, type C(A B).
When A is not nested but B is nested in A, and C is nested in A and B, type B(A) C(A B).
A common example of nesting is when each part is measured by only one operator, such as in destructive testing. In destructive testing, the measured characteristic is different after the measurement process than it was at the beginning. Crash testing is an example of destructive testing.
To use destructive testing, all parts within a single batch must be identical enough to claim that they are the same part. If you cannot make that assumption, then part-to-part variation within a batch will mask the measurement system variation. If you can make that assumption, then choosing between a crossed or nested Gage R&R Study for destructive testing depends on how your measurement process is set up. If all operators measure parts from each batch, then do not specify nesting for Parts and Operators. If each batch is measured by only a single operator, then you must specify nesting for these factors. In fact, whenever operators measure unique parts, you have a nested design.