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!
--- In email@example.com
, Roy Morien <roymorien@...>
> 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
> 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?
> 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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