[R-sig-eco] Compositional Data Analysis: Simplex Scaling Function Selection (Rich Shepard)

[Kari Lintulaakso]

Hi Rich,

you might be interested of http://www.compositionaldata.com/. They have a
forum for CoDa related questions. There seems to be a new R-package for
CoDa: zCompositions.

Cheers,

Kari Lintulaakso

University of Helsinki

On Fri, Sep 26, 2014 at 1:00 PM, <r-sig-ecology-request at r-project.org>
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>    1. Compositional Data Analysis: Simplex Scaling Function
>       Selection (Rich Shepard)
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>
> ----------------------------------------------------------------------
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> Message: 1
> Date: Thu, 25 Sep 2014 15:45:07 -0700 (PDT)
> From: Rich Shepard <rshepard at appl-ecosys.com>
> To: r-sig-ecology at r-project.org
> Subject: [R-sig-eco] Compositional Data Analysis: Simplex Scaling
>         Function        Selection
> Message-ID: <alpine.LNX.2.11.1409251531180.12417 at localhost>
> Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII
>
>    The data sets to be analyzed are proportions based on counts. Each row
> is
> closed; the proportions total 1.00. I understand the need to transform the
> raw data to a CoDA simplex, and my reading strongly suggests that the
> isometric log ratio (ilr) function is the most appropriate for these data.
>
>    In Boogaart and Delgado's "Analyzing Compositional Data With R", page 30
> describes the various available scaling functions. The advice needed is
> which is most appropriate for my data sets:
>    'aplus' -- Aichison (ratio) geometry in the real data space.
>    'rcomp' -- Real (interval) compositional scale.
>    'acomp' -- Aichison (ratio) compositional scale.
> Or, one of the others.
>
>    Reading several docs leaves me confused over which one should be used
> for
> both descriptive statistics and further analyses such as CCA, clustering,
> or
> time series.
>
>    There is no statistics group on stackexchange.com and stackoverflow.com
> is
> for programming questions, not statistical questions. If there is a better
> place for this question, please point me to it as there will be other CoDA
> questions as the analyses proceed.
>
> Rich
>
>
>
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