At 09:31 AM 10/4/2005 +0100, you wrote:
> >Of course, it's always likely that spec's will
> >change (this does not count as an error),
>
>But it could have been an error in the specification ... ;)

Oh, quite possibly (likely, even!), or but I'm compartmentalizing the work,
for the purpose of analyzing errors, even if one person does both tasks.

There are lots of interesting things going on in the process of developing
a totally new product. An error in PCB layout or a 'typo' schematic error
is probably down at the bottom of the 'interesting' scale.

A couple of difficult-to-measure intangibles:

1)      The roach analogy-- if you allow one roach (error) to creep in, then
         more are probably hiding. This applies more to analog circuit design
         and mechanical design than to layout, but it's affected by company
         culture. viz- if the circuit designer knows that there's going to
         be another spin because the layout guy is allowed to make a few
         errors, then she may not be as careful in checking out every worst
         case scenario. This could result in field problems, since the 
prototype
         testing won't usually approach the worst-case in every respect.

2)      The rapid prototyping axiom-- some errors or desirable changes only
         become obvious once you have created a prototype, so you want to get
         there as quickly as possible*, and without investing in things that
         make change financially or temporally difficult (eg. hard tooling).

* In a competitive situation, in some industries, a delay of a couple of
months can *halve* the total profit generated by a product over its
several year lifetime.

>Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff


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