Hi, I am using an IMR (Individuals and Moving Range) chart for short-run SPC. (We do batch-manufacturing of chemical products). Consequently, in some cases, I am lucky to have 100 data points if I use 5 years of data. Is it acceptable to plot 5-years of data on a control chart and use all 5 years of this data to calculate the control limits and Cpk?
IMR (Individuals and Moving Range) Chart for Short-Run SPC - How much data to include
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Re: IMR (Individuals and Moving Range) Chart for Short-Run SPC - How much data to inc
Normally 20 to 25 data are sufficient enough to start calculating the control limits and CpK value.
Moreover it is suggested to use the recent data instead of using the old data (Previous 5 years), because, if there are any changes with respect to Process, machine or material then the changes may not be remembered or assigned if there occurs any shift in the process.
Normally 20 to 25 data are sufficient enough to start calculating the control limits and CpK value.
Moreover it is suggested to use the recent data instead of using the old data (Previous 5 years), because, if there are any changes with respect to Process, machine or material then the changes may not be remembered or assigned if there occurs any shift in the process.
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