[R] fitting model to resampled data

Henrique Dallazuanna
Wed, 29 Sep 2010 20:26:56 -0000

Try this:

growthBoot <- replicate(3, growth[sample(9,12,replace=T),], simplify FALSE)
lapply(growthBoot, nls, formula = Length ~ Linf * (1 - exp(-K * (Age -
to))), start = par)

On Wed, Sep 29, 2010 at 4:56 PM, Michael Larkin
<mlarkin@rsmas.miami.edu>wrote:

> I apologize if this comes across as confusing.  I will try to explain my
> situation as best I can.
>
>
>
> I have R bootstrapping my growth data for fish.  It's resampling my
> database
> of age and length data and then produces several new datasets for me.  In
> this case, it's resampling my data to create three new datasets of age
and
> length data.  Here is my code with my original data called growth:
>
>
>
> replicate(3, growth[sample(9,12,replace=T),], simplify = FALSE)
>
>
>
> This is working very well.
>
>
>
> Now, the problem that I am now stuck with is incorporating a growth model
> into the three new datasets to estimate growth parameters.  Since there are
> now three new datasets I want to get three new estimates of the growth
> parameters, essentially one from each new dataset.
>
>
>
> I am using the von Bertalanffy growth model.  Here is my code:
>
>
>
> par<-list(Linf=700, K=0.20, to=-0.1)
> #these are the starting values for parameters
>
> vb<-nls(Length~Linf*(1-exp(-K*(Age-to))), start=par, data=???)
#this
> is
> the growth model  with the parameters estimated with non linear least
>
> squares (nls)
>
>
>
> I tried placing my resampling function the data part of the nls function
> but
> it asks me for parameter estimates.
>
>
>
> Any advice would be greatly appreciated.
>
>
>
> Mike
>
>
>
>
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>
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>



--
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

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