Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!oliveb!pyramid!prls!philabs!ttidca!hollombe
From: hollombe@ttidca.TTI.COM (The Polymath)
Newsgroups: comp.software-eng
Subject: Re: Using COCOMO to estimate development schedules
Keywords: COCOMO, software development
Message-ID: <4148@ttidca.TTI.COM>
Date: 28 Mar 89 21:57:58 GMT
References: <351@tahoma.UUCP>
Reply-To: hollombe@ttidcb.tti.com (The Polymath)
Organization: The Cat Factory
Lines: 47

In article <351@tahoma.UUCP> lrm5110@tahoma.UUCP (Larry R. Masden) writes:
}I've seen references to a method of estimating software
}development schedules and costs called COCOMO.  I'm interested,
}and I would appreciate some good references or brief descriptions 
}of the system.

This is the system developed by Barry Boehm (pronounced Bame(?)).  I and
my boss at the time attended one of his lectures and acquired copies of
his book in the process.  Two things stick in my mind from that
experience:

1)  His entire system of formulas rests on a figure for the estimated
    difficulty of the project.  My boss and I badgered him for three hours
    to find out where this fundamental figure came from.  When we finally
    pinned him down, the answer he gave amounted to "You take a flying
    guess." (He actually said something about basing the estimate on past
    experience with other projects and the programmers involved.  Given
    that each project is different and involves a different mix of skills
    and people, this amounts to guessing).

2)  My boss, the company's software development manager, then took the book
    home and tried applying COCOMO to figures derived from projects we'd
    already completed.  This man had over 20 years experience in the field
    and routinely made project estimates as part of his job.  He was
    intimately familiar with the work and people involved in the test data
    he used.  The estimates he produced using the COCOMO model differed
    from the actual project completion times by as much as 50%, either
    way.

That said, I'll add that COCOMO is probably at least as good as any other
system available for software development estimates.  The problem is,
there's no good way to estimate something that's different every time you
do it.  I don't think that problem is going to go away for the forseeable
future.

If I used COCOMO, I'd take the results as a ballpark figure, at best, and
add a large grain of salt.

Disclaimer:  The above information is over 5 years old.  In this business,
that means there's a good chance that 50% of it is obsolete or wrong.
Your mileage may vary.

-- 
The Polymath (aka: Jerry Hollombe, hollombe@ttidca.tti.com)  Illegitimati Nil
Citicorp(+)TTI                                                 Carborundum
3100 Ocean Park Blvd.   (213) 452-9191, x2483
Santa Monica, CA  90405 {csun|philabs|psivax}!ttidca!hollombe