1. Individuals Chart Due to High Costs (e.g., destructive testing/measurement) or a lack of data gathering opportunities there may be only one measurement possible in a subgroup. As a rule of thumb, individuals charts should not be used with less than 100 observations. Control limits:

2. Potential Problems With Individuals Charts Correlation in the moving range –Need to be conservative in applying rules 2-5 in the moving range charts. Since the moving ranges are estimates of process variation, inflated control limits can result if the process variation is not stable throughout the sample. –As a rule of thumb, if 2/3 or more of the moving ranges fall below the centerline, inflated control limits use the median of the moving range values instead of the average in calculating control limits

3. Example (problem 7.10, page 275)