<br><font size=2 face="sans-serif">We are working on a project testing
species distribution models against a true population census of shrubs
in southwestern Mongolia. In addition, we are looking at sampling bias
and its effect on predictive ability. We have set up sampling regimes in
R to represent different strategies and biases and are interested in using
BIOMOD to model the distributions.</font>
<br>
<br><font size=3>We have two questions: <br>
</font><font size=2 face="sans-serif"><br>
1) The first question about BIOMOD deals with the independent explanatory
and independent response inputs. Since we have the "truth" in
the shrub census data and are sampling from it, we would like to compare
the sample against the "truth." In other words, instead of splitting
our sample data into training and testing sets, the split would be the
sample and the "truth." I have been reading in the manual about
the independent inputs, and I am confused as to whether or not this is
where we would place the "truth" data. I have included an example
of the initial.state below:</font><font size=3> <br>
</font><font size=2 face="sans-serif"><br>
> Initial.State(Response = sample[,c(27, 28, 29, 30, 31,32,)], Explanatory
= sample[,15:26],</font><font size=3> </font><font size=2 face="sans-serif"><br>
+ IndependantResponse = alldata[,c(27, 28, 29, 30, 31,32,)], IndependentExplanatory
= alldata[,15:26]</font><font size=3> <br>
</font><font size=2 face="sans-serif"><br>
so the object "sample" is a table of our sample of the census,
and the object "alldata" is the census dataset. Is this correct?
If not, is there a way to use the census data set to test the sampled data
in the models?</font><font size=3> <br>
</font>
<br><font size=3>2) We are running multiple batches in a simulation and
errors caused by small sample sizes are causing the simulations to crash.
We would like to allow the modeling to stop but the simulation to loop
to the next larger sample size and continue. Is there a way to trap the
errors and prevent the modeling package from stopping all together?</font>
<br>
<br><font size=2 face="sans-serif">Chris</font>
<br>
<br><font size=2 face="sans-serif">Christopher A. Walter <br>
Biological Science Technician <br>
USGS Leetown Science Center <br>
11649 Leetown Road <br>
Kearneysville, WV 25430 <br>
Phone: 304 724-4479 <br>
<br>
"Its easy not to think when you're not told that much."<br>
-Justin Pierre</font>