Control Chart Builder and skewed variables

[#1]

Hi All. Thanks for reading my question and your time;

I am very inexperienced about the Quality and Process tools. I want to use the Control Chart Builder for the compositional data measured in our lab for a Chinese product. This type of data is skewed some times for some elements, like CaO.

Can I still use the control charts if the data is not normally distributed?

By the way, I have the min and max spec limits for the elements.

Thanks.

[#2]

Thanks a lot. I will ask for the production order and I hope they can find that for me. For the most part what I care about is the consistency of the product that is already manufactured in China and I’m sure that company has done the process control already. But now we want to double check and make sure and also we want to check if something happened on the way to US. We do have to check the ASTM spec limits anyway but it will be helpful maybe to dig deeper with these charts once again and if we find any inconsistency then we can always negotiate with them on pricing etc. for future orders. I hope it makes sense where I’m coming from.

[#3]

If it's worth the effort and that important to your organization, you may want to set up some formal reporting processes between your organization and the supplier. In a former life I was a supplier quality manager at Eastman Kodak Company and I had numerous standard dashboards with process control data for key quality characteristics of materials and services that supplier's were providing to our internal organizations. As examples, we had reporting set up for things like solid ink density for imagery on labels and packing materials (a continuous type variable) and first contact resolution rate (a discrete counting type variable) for an outsourced customer contact center. The overall process was sometimes tied into everything from supplier contracts and sometimes even penalties for noncompliance. We rarely reached the penalty phase, preferring to work collaboratively on Six Sigma type projects when improvement was warranted.

[#4]

@P_Bartell  Thanks for your reply. I think there is also a formal reporting process between my organization and the supplier.