Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!wuarchive!sdd.hp.com!hplabs!otter.hpl.hp.com!hpltoad!cdollin!kers From: kers@hplb.hpl.hp.com (Chris Dollin) Newsgroups: comp.software-eng Subject: Re: Metrics Example Message-ID: Date: 24 May 91 08:11:25 GMT References: <24600@unix.SRI.COM> <1991May23.231339.22418@netcom.COM> Sender: news@hplb.hpl.hp.com (Usenet News Administrator) Organization: Hewlett-Packard Laboratories, Bristol, UK. Lines: 69 In-Reply-To: jls@netcom.COM's message of 23 May 91 23:13:39 GMT Nntp-Posting-Host: cdollin.hpl.hp.com Jim Showalter makes a remark on one of my responses to ... duh, lost their name: [a. n. other] >> I seized on metrics as the answer to my problems. If I could get the >> managers to show me various metric data, then *I* could interpret it >> my own way and make my opinions! [me] >But why should your opinions be any better than theirs? [Jim] His weren't necessarily better. However, what he determined was that the managers didn't have any data to back up their own opinions. Thus, at the outset of the exercise, prior to the introduction of any metrics, all opinions were of equivalent validity/nonvalidity. It was the introduction of the metrics--and ONLY that--that provided a framework in which opinions could be tested against real measures. The point that worries me is this assertion that the metrics are ``real measures''. [I'm happy to believe that they are; it's just that I think they need justification. As earlier posts of mine have said, just because they're *numbers* doesn't make them *meaningful*.] Suppose I proposed the following metrics: * the number of cups (or cans) of beverage consumed per developer per day. * number of charaters of output generated (on paper, that is) per day. * hours spent on aerobics * numbers of relevant papers photocopied per week * average number of windows present on the screen at once Are these ``real measures''? A priori, they seem as real as (say) defect density, or uncommented-lines-of-source-code, or compiles-needed-before-no- syntax errors. You may question the relevance of aerobics [*1]. I might argue ``a fit mind in a fit body''. In any case, one of the points of the original poster was that you could shotgun the team with a variety of metrics and keep those that ``worked'' (whatever that means). If we don't understand why they work (for example, suppose that aerobic hours turned out to be a good predictor for project success), then we should say so. If their effectiveness has be determinded by purely empirical means (ie, we have no underlying theory), we should say so. What we should *not* do is call metrics ``real measures'' without pointing to a justification. Let me try and make my point clear. I want metrics to be a Good Thing; I want to be able to make estimates, plan with them, and measure to see if the plan is being kept to. [I'm not too worried about using numbers to do it, although that's traditional; it's easy to attribute to numbers precision, accuracy, and meaning that they do not in fact posess.] But I think we must be clear as to *why* we thing metrics are ``real'' and *why* we think they work; and we must not allow our enthusiasm to blind us to perfectly sensible questions. What metrics do we have on the effectiveness of posting? [*1] Indeed, many do, even outside this context. -- Regards, Kers. | "You're better off not dreaming of the things to come; Caravan: | Dreams are always ending far too soon."