In Reply to Parent Post by Stijloor
It will help our experts if you can describe the process. Can you be more specific?
Absolutely! We need to know the process and
if any adjustments were made during process. We also need to know the type of characteristic - is it a diameter, length, or other? We also nee to know the measurement technique - as it can often provide more variation than the process itself! By looking at the control limits, this looks likes like a classic sample not representing the total process variation problem. If the evidence shows that to be accurate, then either the charting methodology or the sampling size needs to change. If this is truly the case, an X MR chart attached shows that you have little to apply a corrective action to - except to correct your charting methodology. Even so, without knowing your process and contemplating longer term variation, this may not be the "final answer." We must never blindly assume X-Bar/R is applicable to every situation. It isn't... for some processes it is a terrible option