Average Chart, The averages of the multiple readings by each appraiser on each part are plotted by appraiser with part number as an index. This can assist in determining consistency between appraisers.
The grand average and control limits determined by using the average range are also plotted. The resulting Average Chart provides an indication of “usability” of the measurement system.
The area within the control limits represents the measurement sensitivity (“noise”). Since the group of parts used in the study represents the process variation, approximately one half or more of the averages should fall outside the control limits. If the data show this pattern, then the measurement system should be adequate to detect part-to-part variation and the measurement system can provide useful information for analyzing and controlling the process. If less than half fall outside the control limits then either the measurement system lacks adequate effective resolution or the sample does not represent the expected process variation.
Review of the charts indicates that the measurement system appears to have sufficient discrimination for processes with variation described by the sample parts. No appraiser-to-appraiser differences are readily apparent.
source : Analysis of measurement systems
