Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!ut-emx!tivoli!alan From: alan@tivoli.UUCP (Alan R. Weiss) Newsgroups: comp.software-eng Subject: Re: industrial engineering and metrics (was Re: bridge building and discipline) Message-ID: <773@tivoli.UUCP> Date: 22 May 91 23:27:34 GMT References: <1991May14.150350.2837@den.mmc.com> <1991May15.180943.6796@netcom.COM> <1991May15.223135.12381@m.cs.uiuc.edu> <1991May16.151913.13770@weyrich.UUCP> Reply-To: alan@tivoli.UUCP (Alan R. Weiss) Organization: Tivoli Systems Inc., Austin, TX Lines: 89 In article <1991May16.151913.13770@weyrich.UUCP> orville@weyrich.UUCP (Orville R. Weyrich) writes: >In article <1991May15.223135.12381@m.cs.uiuc.edu> marick@m.cs.uiuc.edu (Brian Marick) writes: >>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. Measuring the long-term cost of quality is difficult, and can only be done *after* the firm has experienced the cost of re-work, warranties, and lost sales AND they have surveyed their (former) customers to determine defection causes. Like I said, difficult. Some have actually done it, though, and some have indeed gone on faith (see below): >>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. This is actually incorrect. Deming and other Modern Quality Theorists insist upon Statistical Process Control to measure the Cost of Quality. I refer you to Crosby, Gilb, Demings, Juran, et al. >If you can't measure something, you can't control it or set priorities. >I conclude that effective metrics are essential to improvements in software >quality. HOWEVER ... see below. You can certainly control the most important factor in software development (according to Tony DeMarco in Peopleware), the environment/culture, without measurements. Its not XOR, its AND. You need the metrics for the development process, cost analysis, and to pinpoint specific areas of improvement. But you can in fact manage quite well without them. You may not end up with QUALITY, that's all. :-) >>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. > >There is a real problem with the Hiesenberg uncertainty principle Yes, this can be true. That's part of the improvement process: the mere knowledge of observation can have an improvement effect, which is more properly attributed to the Hawthorn Effect (GE, 1923 study in which the changing of ANY environment variable improved productivity!). >Is Motorola's current position on drug testing an aspect of their >being fanatical? :-) It seems that impairment testing [which they do not do] >would be more effective in improving quality. See the recent discussion >in misc.jobs.misc. From what I gather from folks who have left Moto-Austin, it is some kind of personal crusade or something of selected individuals. Weird, and surprisingly unscientific. >-------------------------------------- ****************************** >Orville R. Weyrich, Jr., Ph.D. Certified Systems Professional >Internet: orville%weyrich@uunet.uu.net Weyrich Computer Consulting >Voice: (602) 391-0821 POB 5782, Scottsdale, AZ 85261 >Fax: (602) 391-0023 (Yes! I'm available) >-------------------------------------- ****************************** _______________________________________________________________________ Alan R. Weiss TIVOLI Systems, Inc. E-mail: alan@tivoli.com 6034 West Courtyard Drive, E-mail: alan@whitney.tivoli.com Suite 210 Voice : (512) 794-9070 Austin, Texas USA 78730 Fax : (512) 794-0623 _______________________________________________________________________