If any of the points on the R-chart go above the upper control limit (UCL) or are below the lower control limit (LCL), that operator is having difficulty consistently measuring that part or parts. The UCL value takes into account the number of times an operator measures a part. If operators are measuring consistently, these ranges should be small relative to the data and the points should be in statistical control. Technician 3 appears to be the most repeatable technician based on the R chart.
Note: The R chart is displayed when the number of replicates is less than 9. Otherwise, an S chart is displayed