I-MR-R Chart in Excel using QI Macros

I-MR-R Chart in Excel

The I-MR-R chart is a combination of XbarR and XmR Chart. It gives both "within" group and "between" group variation, It:

• Calculates the average of subgroups, just like an XbarR
• Creates the Range chart (within group variation) just like the XbarR
• Creates a Moving Range Chart (between group variation) like an XmR using the average of the subgroups.
• Creates the Individuals Chart like an XmR using the average of the subgroups.

Watch I-MR-R Chart Video

How to Create an I-MR-R Chart:

1. Select two or more columns of data.
   
2. Click on the QI Macros pull-down or ribbon menu, select Control Charts then "I-MR-R chart".
3. Enter titles for your charts when prompted:
• X or Individuals chart
• MR - Moving Range
• R - Range
  
4. Analyze and interpret the results:
   • Evaluate the range charts first. If they are "out of control," so is the process. If the range charts look okay, then evaluate the X chart.
   • Unstable points or trends will turn red and need to be investigated.

You can also create the chart using prior versions of the QI Macros XbarR and XmR Charts:

Here's how to do it with the QI Macros:

1. Run an XbarR Chart on your data to get the R Chart (or XbarS chart if you want the S Chart).
2. Select the averages calculated for this chart (hiding behind the Xbar and R Charts) and run an XmR (I-MR) chart on the averages.
3. Copy the R chart from the XbarR chart to the XmR charts and you'll have an I-MR-R chart.
   
   

Example using XbarR Test data:

1. Run an XbarR Chart on your data (two or more samples) to get the R Chart
   (or run an XbarS chart if you want the S Chart):
   
   
   
   
2. Select the averages calculated for this chart (hiding behind the Xbar and R Charts) and run an XmR (I-MR) chart on the averages.
   
   
   
   
3. Copy the R chart from the XbarR chart (or S Chart from XbarS Chart) to the XmR charts and you'll have an I-MR-R/S chart.
   
   
   
   

This gives the following:

• An Individuals chart of the subgroup means
• A moving range chart of the subgroup means (Between)
• A range chart of the subgroups (Within)

It takes two steps, but produces the desired charts.