Re: KP Rule*

[David Kerridge <dfkerridge@mac.com>]

t info would I need to make an argument that the Kp rule is superior to traditional Acceptance Sampling?  What exactly are the calculations?  Thanks.


All the details are in Chapter 15 of "Out of the Crisis", entitled


"Plan for Minimum Average Total Cost for Test of Incoming
Materials and Final Product."


It is easy to forget that this chapter exists, as it seems at first to
be out of tune with the overall message of the book. So let us
reflect for a moment on why this chapter is needed.


In an ideal world, mass inspection is a waste of time and money.
As point 3 puts it "Cease dependence on inspection to achieve
quality. Eliminate the need for inspection on a mass basis by
building quality into the product in the first place."


But there is a great problem. You cannot always eliminate the
need for inspection. When, as in papermaking, or whisky
distilling, you depend on biological raw materials, they
will vary. You must either make your processes insensitive
to variation, or use inspection of incoming materials.


Equally you cannot always achieve the required level of reliability
(or public conidence) without 100% inspection. Noone would fly in
an aeroplane that was not checked regularly.


The value of Chapter 15 is that it tells you whether inspection is
needed, and when to stop. It also demonstrates one of the many
advantages of statistical control, since if this is achieved inspection
becomes cheaper, if needed, and less likely to be needed at all.


-- 

Best wishes

David

dfkerridge@mac.com