X Median R Chart Formulas
The XMedianR chart works just like the XbarR chart except that it uses the median instead of the average as a measure of central tendency.
Here are the X Median R chart formulas used in QI Macros for both the Range and Median charts.
Range Chart formula
X Median Chart
n = number of samples in a subgroup
k = number of subgroups used to determine the average median and range
Conforms with AIAG SPC 2nd Edition
Process: Calculate, plot, and evaluate the range chart first. If it is "out of control," so is the process. If the range chart looks okay, then calculate, plot, and evaluate the X chart.
- Create a X Median R chart in Excel using QI Macros
- View all six sigma charts and tools in QI Macros
- Other control chart formulas
The X Median R chart is just one of the tools included in the QI Macros for Excel SPC Software for Excel.
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