Quality and Reliability Methods - SAS

Chapter 10 Variability Charts 177
Attribute Gauge Charts
Figure 10.21 Effectiveness Report
The Agreement Counts table gives cell counts on the number correct and incorrect for every level of the
standard.
Effectiveness is defined as (# of correct decisions) / (Total # of opportunities for a decision).
This means that if rater A sampled every part four times, and on the sixth part, one of the decisions did not
agree, the other three decisions would still be counted as correct decisions.
Note: This is different from the MSA 3 rd edition, as all four opportunities for rater A by part 6 would be
counted as incorrect. We feel including all inspections separately gives the user more information about the
overall inspection process.
In the Effectiveness Report, 95% confidence intervals are given about the effectiveness. JMP is using
Score Confidence Intervals. In recent literature, it has been demonstrated that score confidence intervals
provide more sensible answers, particularly where observations lie near the boundaries. (See Agresti and
Coull , 1998.)
The Misclassifications table shows the incorrect labeling with the y-axis representing the levels of the
standard, or accepted reference value, and the x-axis containing the levels given by the raters.
The Conformance Report displays the probability of false alarms, and the probability of misses, where
• False Alarm = part is determined non-conforming, when it actually is conforming