Used to evaluate the repeatability and reproducibility of a measurement system used to measure a continuous variable. This tool is used when parts cannot be measured multiple times by multiple appraisers (for example, destructive testing in which the homogeneous batch size is too small to accommodate multiple tests by multiple operators). This analysis requires that you choose groups of parts similar enough so they can be considered the same part; otherwise, the part variation will mask the measurement variation. You should answer the question of whether you can trust your data before you calculate a baseline or attempt any improvement.
|When to Use||Purpose|
|Start of project||Verify you can precisely measure process outputs before attempting to perform a baseline analysis.|
|Mid-project||Verify you can precisely measure process inputs being investigated.|
|End of project||Verify you precisely measure process outputs after improvements have been made. It is not uncommon to reduce variation to a point where you cannot do so with the pre-improvement measurement system.|
|End of project||Verify you can precisely measure critical process inputs that must be controlled to maintain the improvements. These should have been already verified earlier in the project.|
Continuous Y, two X-variables (typically Operator and Part); typically for destructive testing evaluation.