Re: [office] Re: [office-comment] Re: sigmoid curve fitting in trend lines

[Andreas J Guelzow <andreas.guelzow@concordia.ab.ca>]

Well, personally I see little point in specifying an attribute value
that will not lead to any interoperability. In that case I think it is
much better to allow name-spaced attribute values so that different
implementations can easily add their favourite best-fit lines, or at
least only add attribute values if at least one implementation is
willing to implement it and describe its algorithm.

Just adding an attribute value nobody supports seems to be pointless.

Andreas


On Mon, 2012-11-05 at 13:04 -0700, robert_weir@us.ibm.com wrote:
> office@lists.oasis-open.org wrote on 10/26/2012 12:32:24 AM:
> 
> > From: "Andreas J. Guelzow" <andreas.guelzow@concordia.ab.ca> 
> > To: office@lists.oasis-open.org, 
> > Date: 10/26/2012 12:32 AM 
> > Subject: Re: [office] Re: [office-comment] Re: sigmoid curve fitting
> > in trend lines 
> > Sent by: office@lists.oasis-open.org 
> > 
> > On Thu, 2012-10-25 at 15:57 -0600, robert_weir@us.ibm.com wrote:
> > > I'm not sure we want to specify the method used to fit the curve.
>  We
> > > should probably specify the outcome.   The specific algorithm used
> > > might vary according to the processor, number of processors, etc. 
> > > 
> > > I'm sure Andreas would have some ideas, but I wonder if we could
> say
> > > something like, "Uses an implementation-defined method to fit a
> > > sigmoid curve to the data while minimizing the average squared
> > > deviation".  Then we're specifying the outcome, but allowing fo
> > > innovation in the method.
> > 
> > 
> > Are we sure that the proposals (and the calculation supposedly
> outlined
> > in those papers I haven't read,) in fact create a curve that
> minimizes
> > the average squared deviation?
> > 
> > I am not used to R, but looking at the example referenced in a
> previous
> > message in this thread and considering R's SSlogis function it seems
> to
> > me that R's fitting depends not only on the data but also on three
> > initial values. Are we sure that there is a unique sigmoid function
> that
> > can be fitted to a given set of data?
> > 
> > If there is more than one than a generic description as above will
> not
> > provide for interoperability.
> > 
> 
> So what are our choices? 
> 
> 1) Say something in very general terms, like: "attempts a 'best fit'
> of the data to the following model:" This allows implementations to
> vary on the quality of the fit, but doesn't guarantee identical
> results.  So similar to IRR(). 
> 
> 2)Cite a specific algorithm, with the risk that it might not be the
> best one today, or the best one 5 years from now.  But it will give
> the same results to the extent everyone implements the cited
> algorithm. 
> 
> IIRC once you get beyond linear models, or ones that can be
> transformed to linear models, you no longer generally have simple
> techniques that easily yield the same answer.  You have optimization
> heuristics that will depend not only on parameters of the mode, but
> also parameters of the algorithm, like step size, number of
> iterations, etc.  So although in theory we could do #2, wouldn't we be
> 2nd guessing the implementor on a lot of these details? 
> 
> -Rob 
> 
> > Andreas
> > 
> > 
> > > 
> > > 
> > > Patrick Durusau <patrick@durusau.net> wrote on 10/25/2012 05:26:46
> PM:
> > > 
> > > > From: Patrick Durusau <patrick@durusau.net> 
> > > > To: James Salsman <jsalsman@gmail.com>, 
> > > > Cc: office-comment@lists.oasis-open.org 
> > > > Date: 10/25/2012 05:26 PM 
> > > > Subject: Re: [office-comment] Re: sigmoid curve fitting in trend
> > > lines 
> > > > 
> > > > James,
> > > > 
> > > > First, thanks for the references!
> > > > 
> > > > Second, standards can refer to other standards but generally not
> to 
> > > > periodical literature as normative.
> > > > 
> > > > Which means we will have to extract the necessary definitions
> and 
> > > > incorporate them in the text.
> > > > 
> > > > I will grab copies of them in the next day or so to see what
> that
> > > will take.
> > > > 
> > > > Hope you are having a great week!
> > > > 
> > > > Patrick
> > > > 
> > > > On 10/24/2012 09:43 PM, James Salsman wrote:
> > > > > Patrick,
> > > > >
> > > > > Thank you for your question.
> > > > >
> > > > > First, please change "Gompertz sigmoid – Regression with a
> > > > > logistic...." to "Gompertz sigmoid – Regression with a
> > > Gompertz...."
> > > > > on the fifth line of my original request below.  I'm sorry
> about
> > > that
> > > > > typo, and I tried to fix it, but it apparently didn't get
> fixed in
> > > my
> > > > > request.
> > > > >
> > > > > As for the methods of calculating the parameters for fitting
> those
> > > two
> > > > > very important curves, instead of trying to describe them,
> could
> > > you
> > > > > please reference these authoritative descriptions of the
> > > algorithms
> > > > > instead?
> > > > >
> > > > > For logistic curve fitting: J. A. Nelder (March 1961) "The
> Fitting
> > > of
> > > > > a Generalization of the Logistic Curve" _Biometrics_ vol. 17,
> no.
> > > 1,
> > > > > pp. 89-110: http://www.jstor.org/stable/2527498
> > > > >
> > > > > For Gompertz curve fitting: Karl W. Kaufmann (1981) "Fitting
> and
> > > using
> > > > > growth curves" _Oecologia_ vol. 49, no. 3, pp. 293-299:
> > > > > http://www.springerlink.com/content/w153v81q72400q62
> > > > >
> > > > > Please let me know if I can help any further.
> > > > >
> > > > > Best regards,
> > > > > James Salsman
> > > > >
> > > > >
> > > > > On Wed, Oct 24, 2012 at 3:28 PM, Patrick Durusau 
> > > > <patrick@durusau.net> wrote:
> > > > >> James,
> > > > >>
> > > > >> With regard to your request for the addition of:
> > > > >>
> > > > >>> "* logistic sigmoid – Regression with a logistic sigmoid
> > > function –
> > > > >>> approximate the values of the series using the model: y =
> > > > >>> A+B/(1+e^(-(x-C)/D))
> > > > >>>
> > > > >>> "* Gompertz sigmoid – Regression with a logistic sigmoid
> > > function –
> > > > >>> approximate the values of the series using the model: y =
> > > > >>> A+B·e^(C·e^(D·x))"
> > > > >>
> > > > >> To the ODF standard.
> > > > >>
> > > > >> Can you define the method for calculating the parameters of
> these
> > > two
> > > > >> functions?
> > > > >>
> > > > >> Please pardon our delay in reaching your request.
> > > > >>
> > > > >> The TC has not made a decision about your request but having
> the
> > > additional
> > > > >> information will make that task easier.
> > > > >>
> > > > >> Thanks!
> > > > >>
> > > > >> Hope you are having a great week!
> > > > >>
> > > > >> Patrick
> > > > >>
> > > > >> --
> > > > >> Patrick Durusau
> > > > >> patrick@durusau.net
> > > > >> Former Chair, V1 - US TAG to JTC 1/SC 34
> > > > >> Convener, JTC 1/SC 34/WG 3 (Topic Maps)
> > > > >> Editor, OpenDocument Format TC (OASIS), Project Editor
> ISO/IEC
> > > 26300
> > > > >> Co-Editor, ISO/IEC 13250-1, 13250-5 (Topic Maps)
> > > > >>
> > > > >> Another Word For It (blog): http://tm.durusau.net
> > > > >> Homepage: http://www.durusau.net
> > > > >> Twitter: patrickDurusau
> > > > >>
> > > > 
> > > > -- 
> > > > Patrick Durusau
> > > > patrick@durusau.net
> > > > Former Chair, V1 - US TAG to JTC 1/SC 34
> > > > Convener, JTC 1/SC 34/WG 3 (Topic Maps)
> > > > Editor, OpenDocument Format TC (OASIS), Project Editor ISO/IEC
> 26300
> > > > Co-Editor, ISO/IEC 13250-1, 13250-5 (Topic Maps)
> > > > 
> > > > Another Word For It (blog): http://tm.durusau.net
> > > > Homepage: http://www.durusau.net
> > > > Twitter: patrickDurusau
> > > > 
> > > > 
> > > > -- 
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> > 
> > -- 
> > Andreas J. Guelzow, PhD, FTICA
> > Concordia University College of Alberta
> > [attachment "signature.asc" deleted by Robert Weir/Cambridge/IBM]

-- 
Andreas J. Guelzow, PhD FTICA
Professor of Mathematical & Computing Sciences
Concordia University College of Alberta

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