That pure Cane Spirit since 1848.

Monday, March 12, 2007

Best fit polygon and controlling variables as a means of quality assurance.

Kim’s last post but one has spurred me to bend my wits upon a conjecture he has propounded.

‘Best fit polygon’ is an engineering technique (surprise surprise) to help in the evaluation of component design.

Bear with me, there’s no test at the end.*

Imagine if you will, a component of a machine that must achieve 4 criteria and each of these criteria is of equal importance. If we were to describe these requirements graphically [draw them out on graph paper] it might look like a square. Still with me? Good. Now imagine that 2 of the requirements were each twice as important as the other two, the resultant shape would now be a rectangle twice as long as it’s broad. OK still? Fine.

Well in reality there might be 10 or more important qualities that the thing must have and each of varying importance, so you end up with a complicated shape.
What you then do is go through the alternatives until you find a design that best fits that shape. We call that the ‘optimum’ design.
Of course some qualities might totally override others and therefore must be achieved whatever the cost, so you can end up with some pretty funny shapes I can tell you. We had one once that looked for all the world like a great big
I digress.

It’s all done on computers by low paid graduate trainees, the point is, it is a system of compromise. It has to be.

Stick with me Ayres, I beg you.

The next thing is ‘controlling the variables‘. Formalised by the Americans in the second world war, they realised that if you removed the variables from the manufacturing process, then any resultant deviation was due to random chance and not worth crying about. The trick being separating out what you must and what you can’t control.

Phew! Now we’re at the bone.

If, and it’s only a proposition mind, we apply these trusted techniques to our own life situation, do we,-

a) end up in an optimum world?
b) end up in an ideal world?


c) which is the world described by the philosopher Ayres?
d) are the two worlds equivalent?

Answers in by Founder’s Day please, one side of the paper only and two inch margins.

* I totally lied.

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