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<font face="Times New Roman, Times, serif">Dear Andreia,<br>
Yes, it seems the neural networks do not work with very few points. It
is not a very good practice of fitting models with so little
information.<br>
These models are correlative. They cannot be properly adjusted with
very few points. <br>
<br>
First, remove the neural networks from your runs. They are pretty
sensitive to sample size. Then run the other ones. With a bit of
chance, the other would fit. <br>
<br>
Hope it helps,<br>
Wilfried<br>
<br>
<br>
</font><br>
Andreia Mendonça a écrit :
<blockquote
cite="mid:ea788aea0903191022r7799560bieea75b3a12f58447@mail.gmail.com"
type="cite">Hello all,<br>
<br>
I am using BIOMOD to model some data, but I'm facing some errors that i
can't seem to overcome.<br>
<br>
As i tried to run the models on some of the populations, the following
error showed up in R:<br>
<pre><font style="font-family: arial,helvetica,sans-serif;" size="2"><b><font
style="font-family: arial,helvetica,sans-serif;" size="2">Error in nnet.default (x, y, w,...): </font></b></font><b
style="font-family: arial,helvetica,sans-serif;"><font
style="font-family: arial,helvetica,sans-serif;" size="2">initial value in 'vmmin' is not finite
</font></b><span style="font-family: arial,helvetica,sans-serif;"><font
style="font-family: arial,helvetica,sans-serif;" size="2">The error only happens when I try to model populations with 12, 9 or 7 individuals. When i model populations with 40, 26, 19 or even 14 individuals it works just fine.
So this error has to do with the sample size? Is there any way to solve this?
</font></span><span style="font-family: arial,helvetica,sans-serif;"><font><font
style="font-family: arial,helvetica,sans-serif;" size="2">I really appreciate all the help you can give me, since i am much of a newbie with modelling methods.
*Andreia*
</font></font></span></pre>
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<br>
<pre class="moz-signature" cols="72">--
--
Wilfried Thuiller
Laboratoire d'Ecologie Alpine, UMR-CNRS 5553
Université J. Fourier
BP 53, 38041 Grenoble Cedex 9, France
Tel: +33 (0)4 76 63 54 53
Fax: +33 (0)4 76 51 42 79
Email: <a class="moz-txt-link-abbreviated" href="mailto:wilfried.thuiller@ujf-grenoble.fr">wilfried.thuiller@ujf-grenoble.fr</a>
Home page: <a class="moz-txt-link-freetext" href="http://www.will.chez-alice.fr">http://www.will.chez-alice.fr</a>
Website: <a class="moz-txt-link-freetext" href="http://www-leca.ujf-grenoble.fr/equipes/tde.htm">http://www-leca.ujf-grenoble.fr/equipes/tde.htm</a>
FP6 European MACIS project: <a class="moz-txt-link-freetext" href="http://www.macis-project.net">http://www.macis-project.net</a>
FP6 European EcoChange project: <a class="moz-txt-link-freetext" href="http://www.ecochange-project.eu">http://www.ecochange-project.eu</a></pre>
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