Newsgroups: comp.software-eng
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!m.cs.uiuc.edu!marick
From: marick@m.cs.uiuc.edu (Brian Marick)
Subject: industrial engineering and metrics (was Re: bridge building and discipline)
Message-ID: <1991May15.223135.12381@m.cs.uiuc.edu>
Organization: University of Illinois, Dept. of Comp. Sci., Urbana, IL
References: <1991May9.053311.800@netcom.COM> <4563.282e83ea@iccgcc.decnet.ab.com> <JGAUTIER.91May13125016@vangogh.ads.com> <1991May14.150350.2837@den.mmc.com> <1991May15.180943.6796@netcom.COM>
Date: Wed, 15 May 1991 22:31:35 GMT

jls@netcom.COM (Jim Showalter) writes:

>I find it odd that metrics have been
>successfully used in just about all other industries to improve quality,
>reduce risk, identify incipient problems, increase productivity, etc, but

Let's be careful.  For example, consider industrial engineering, where
people used to measure "cost of quality".  The cost of quality was
calculated by adding together two curves.  The first curve was the
cost of shipping bad product, which decreases with increasing
inspection.  The second is the cost of inspection itself, which
obviously increases.  Businesses strived to position themselves at the
minimum, the "acceptable quality level".

This turns out to be a bad idea.  The root problem is that it's very
hard to measure the true cost of shipping bad product.  For example,
how do you measure low-level annoyance with rattling parts --
something that doesn't result in a warrantee charge, but may mean the
customer buys another brand next time?  This incomplete data then led
directly to mistaken strategies.

The modern approach, following Taguchi, Deming, and company, has (in
principle) abandoned a measurement (cost of quality) and replaced it
with a system of faith that asserts that increased quality is *always*
cost-effective.  In this case, the faith has worked better than the
metric.

I'd guess that a sizable percentage of the anti-metric camp is
justifiably fearful of the effects of measuring (and, inevitably,
concentrating on) the inessentials.  Another sizable percentage is
spoiled rotten.

Disclaimer:  I'm not an industrial engineer.  What I know, I know from
taking industrial engineering courses, reading, and being an employee
of a company that's been quite successfully fanatical about quality.

Further disclaimer:  And, of course, even I realize my capsule summary
of industrial engineering is over-simplified.

Brian Marick
Motorola @ University of Illinois
marick@cs.uiuc.edu, uiucdcs!marick