TOPIC: DOE in Manage Quality

Hi, I'm getting a little confused with the Design of Experiments tool and why it is situated in Manage Quality. This tool is used to determine which variables affect quality and can be used to come up with quality procedures, cheaper ways to complete the same quality processes. This is the same purpose with Alternative Analysis. I.e. you are looking for alternatives for the best processes. Aren't these tools better used in a Plan Quality output? Your insight will will be greatly appreciated!

thanks

Faraz