I would like to discuss related to the creation of the Turtle Diagram based on the QMS processes.
Basically there are 16 main QMS processes. Does it mean I need to create the Turtle Diagram based on this 16 process? Or can I make it into separate Turtle Diagram? Is it possible to have Turtle Diagram that is not related to these 16 process?
Turtle Diagram has to be created for all 16 main QMS processes, as this is a process-oriented approach commonly used in the automotive industry. It is not one diagram, you need to have all 16 Turtle Diagrams as those processes represent your core business process. Also, processes that are commonly defined by Turtle diagram are Market analyses/customer requirements; Request for quotation/tender; Product emergence process; Product and process verification/validation; Order handling/product manufacturing; Delivery; Change management; Warranty/complaint process; Customer service/customer feedback.
If I have understood you correctly, the size of your subgroup will be 1. If you have only 1 piece, you cannot calculate standard deviation because there is no standard deviation if there is no more than 1 piece. You will need to have a sample of more than 30 to get valid statistical data.