Use JMP to Implement an Attribute MSA
Data File: “AttributeMSA.jmp”
Steps in JMP to run an attribute MSA:
- Click Analyze -> Quality & Process ->Variability/Attribute Gauge Chart
- Select “Appraiser A”, “Appraiser B” and “Appraiser C” as “Y, Response”
- Select “Part” as “X,Grouping”
- Select “Reference” as “Standard”
- Select “Attribute” as the “Chart Type”
- Click “OK”
- Click on the red triangle button next to “Attribute Gauge”
- Click “Show Effectiveness Points”
- Click “Connect Effectiveness Points”
Percentage of agreement by appraiser
- Red line: the percentage of agreement with the reference level
- Blue line: the percentage of agreement between and within the appraisers
- When both lines are at 100% level across parts and appraisers, the measurement system is perfect
- % Agreement: Overall agreement percentage of both within and between appraisers. It reflects how precise the measurement system performs
- In this example, 78% of items inspected have the same measurement across different appraisers and also within each individual appraiser
- Rater Score: the agreement percentage within each individual appraiser
Kappa statistic is a coefficient indicating the agreement percentage above the expected agreement by chance. Kappa ranges from −1 (perfect disagreement) to 1 (perfect agreement). When the observed agreement is less than the chance agreement, Kappa is negative. When the observed agreement is greater than the chance agreement, Kappa is positive. Rule of thumb: If Kappa is greater than 0.7, the measurement system is acceptable. If Kappa is greater than 0.9, the measurement system is excellent.
The first table shows the Kappa statistic of the agreement between appraisers. The second table shows the Kappa statistic of the agreement between individual appraiser and the standard. The bottom table shows the categorical kappa statistic to indicate which category in the measurement has worse results.
Model summary: Count of true positives, true negatives, false positives and false negatives. The effectiveness shows the percentage of the agreement between each appraiser and the standard. It reflects the accuracy of the measurement system.