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Re: Help with The Inevitable Question

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  • hmeftah
    Hi Simon, Many of my clients ask the same question. How estimate revamping an existing application. You have to start from concrete facts: 1) your current
    Message 1 of 38 , Sep 1, 2008
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      Hi Simon,

      Many of my clients ask the same question. How estimate revamping an
      existing application.

      You have to start from concrete facts:
      1) your current application even it's not perfect works every day.
      2) Your application is based on VB code, therefore this code is
      the latest version of your application documentation.
      3) You know all functions and methods, screens, data structure and
      so on.
      4) you may know how long a new feature took to be designed
      developed and tested.

      For my point of view your project is quite large so you may need a
      proof of concept phase to estimate time and budget.
      I think your gradual revamping is a good approach, upon these 4 basic
      facts above you can estimate and budget for example section X which
      will use that method, that class, this sort of data structure, this
      database access. Use "playing cards" Scrum phase to estimate our team
      velocity at day one.
      Then refine your figures by using COCOMOII analysis, function points
      estimate and add some contingency.

      Good luck

      H. Meftah
    • ceezone
      I agree with whatever you are saying Roy. But these are my observations/experience: 1. Most project managers have, heard of/Used (even if poorly)/considered,
      Message 38 of 38 , Sep 25, 2008
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        I agree with whatever you are saying Roy.

        But these are my observations/experience:

        1. Most project managers have, heard of/Used (even if
        poorly)/considered, Function points.

        2. Very few have heard of Use case points.

        3. Almost no one has heard of COCOMO (shame)

        Someone somewhere (blast my memory) has made a very valid point about
        estimations showing a graph which corresponds to one of a the
        economics curve of law of diminishing marginal returns. This is a
        curve of estimation accuracy.vs.effort expended on arriving at the
        estimate. I think lot of organisation forget that!

        cheers
        Cheenie




        --- In scrumdevelopment@yahoogroups.com, Roy Morien <roymorien@...>
        wrote:
        >
        > Wonderful!! Apply mathematics and metrics (COCOMO-II - because
        COCOMO-I was found to be deficient and in need of improvement) and
        Function Points, which look great because of the emphasis on metrics
        and measurement and historical 'facts' ... and THEN ADD SOME
        CONTINGENCY ... which clearly indicates that all those metrics and
        measurements and estimating methods don't work very well ... and ...
        ummm ... what is the measure of 'some' in that 'add some contingency'
        bit?I'm sorry to be appearing to ridicule your suggestion, H. but ...
        well, yes, I am ridiculing your suggestion.
        >
        > My advice to Simon would be to first ask the clients to give a full
        and accurate statement of requirements, and a clear contractual
        undertaking that if it is not stated in that specification, then it
        will not be included in the developed system. The client must provide
        that spec in sufficient detail for you to give an estimate of
        sufficient correctness. They surely are not so unreasonable as to ask
        you for accuracy without them also being accurate and correct and
        comprehensive.
        >
        > If the existing system can be seen as being exactly what they want,
        and so can be pointed to as the spec., then one may ask the question
        Why on earth are they asking for a rewrite?
        > An interesting fact that arose from my research (albeit a
        reasonably restricted research activity to admit to the facts) into
        software estimating. I researched amongst consulting firms and
        contracting firms that represented well over 50% of the local
        industry in my home city; not one of them used COCOMO of any vintage,
        and not one of them used Function Point Analysis, and many of the
        project managers had never heard of COCOMO or Function Points. Do I
        come from the real boondocks of software projects?
        >
        > Regards,
        > Roy Morien
        >
        >
        >
        > To: scrumdevelopment@...: hmeftah@...: Mon, 1 Sep 2008 09:16:55
        +0000Subject: [scrumdevelopment] Re: Help with The Inevitable Question
        >
        >
        >
        >
        > Hi Simon,Many of my clients ask the same question. How estimate
        revamping anexisting application.You have to start from concrete
        facts: 1) your current application even it's not perfect works every
        day. 2) Your application is based on VB code, therefore this code
        isthe latest version of your application documentation.3) You know
        all functions and methods, screens, data structure andso on.4) you
        may know how long a new feature took to be designeddeveloped and
        tested.For my point of view your project is quite large so you may
        need aproof of concept phase to estimate time and budget. I think
        your gradual revamping is a good approach, upon these 4 basicfacts
        above you can estimate and budget for example section X whichwill use
        that method, that class, this sort of data structure, thisdatabase
        access. Use "playing cards" Scrum phase to estimate our teamvelocity
        at day one.Then refine your figures by using COCOMOII analysis,
        function pointsestimate and add some contingency.Good luckH. Meftah
        >
        >
        >
        >
        >
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