The I-MR chart is best for: The natural subgroup size is unknown. The integrity of the data prevents a clear picture of a logical subgroup. The data is scarce (therefore subgrouping is not yet ...

The characters used in the chart and the values that they represent are given in a legend at the bottom of the chart. The subgroup symbols are ordered A through Z and 0 through 9 with the characters ...

and R Charts with Varying Subgroup Sample Sizes Note that the central line on the R chart and the control limits on both charts vary with the subgroup sample size. The sample size legend in the lower ...