I work for a manufacturing facility and we use a program called Minitab which is a statisical program that generates charts and capabilities based on the data received. I need help trying to figure out how Minitab is calculating a variable called Rbar. Attached you will see some sample charts where the Range is calculated. The value Minitab is getting is .00821 where when I do it manually I am getting .0115. I need to figure out how and why there is a variation in the values as I need to run some calculations manually.
First person that can explain this to me and how me how I can get .00821 will win the project. I only have $30 to spend on this so please bid accordingly.
Attached is the outputted graphs as well as a csv file containing the data points. (use subgroup sizes of 3 as you can see from the graphs)