Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uwm.edu!linac!att!cbnews!cbnewsm!lfd From: lfd@cbnewsm.att.com (leland.f.derbenwick) Newsgroups: comp.software-eng Subject: Re: Code inspections Summary: inspection rate Message-ID: <1991Jan29.225747.5703@cbnewsm.att.com> Date: 29 Jan 91 22:57:47 GMT References: <14964@megatest.UUCP> <1991Jan28.225231.19444@ico.isc.com> Organization: AT&T Bell Laboratories Lines: 43 In article <1991Jan28.225231.19444@ico.isc.com>, rcd@ico.isc.com (Dick Dunn) writes: > pat@megatest.UUCP (Patrick Powers) writes: > ... > > Though there is plenty of evidence that code inspections are cost > > effective, I believe they would tend to be boring and stressful. > > Boring because they are a time consuming and non-creative activity -- > > current issue of IEEE Software recommends 150 lines of code reviewed > > per man-day as a good figure... > > Well, we all know that lines of code is a lousy measure of anything except > the number of newlines (don't we?:-), but still, if this measure is any- > where close to real, it's a much stronger argument that Powers suggests > against code inspections. A halfway-decent programmer can produce several > times that 150 l/d figure...proceeding through anything at 20 lines/hour > (that's 3 minutes per line, effectively???) is too slow to feel productive. The figure was 150 lines per person-day: effort, not time. Since a typical "full" code inspection involves (1) the author, (2) the moderator, (3) the reader, (4,5) a couple of other inspectors, that comes to 150 lines in about 1.6 hours per person, average. That seems quite reasonable, assuming 150 LOC inspected per hour, plus a reasonable amount of preparation time for all participants. (There have been some studies indicating that you can get by with the author, a combined reader/moderator, and one other inspector, or similar "reduced" inspections, without letting too many more errors get by. Assuming the same effort per individual, that increases the inspection productivity to about 250 LOC per person- day.) On a separate issue, most references indicate an average productivity across an entire project (counting effort for documentation, etc.) somewhere in the range of 5 to 20 LOC per person-day. Given that coding is something like 1/6 of total effort, that still leaves typical coding rates (assuming the modules are fully designed) in the range of 30 to 120 LOC per person-day, much less than you seem to assume. (Certainly there are bursts at much higher rates, and a few people [Ken Thompson?] can probably sustain much higher rates. But it isn't common.) -- Speaking strictly for myself, -- Lee Derbenwick, AT&T Bell Laboratories, Warren, NJ -- lfd@cbnewsm.ATT.COM or !att!cbnewsm!lfd