On May 14, 2010, at 11:57 AM, David Winsemius wrote:


On May 14, 2010, at 11:41 AM, Claudia Penaloza wrote:

(corrected version of previous posting)

I fit a GAM to turtle growth data following methods in Limpus & Chaloupka
1997 (http://www.int-res.com/articles/meps/149/m149p023.pdf).

I want to obtain figures similar to Fig 3 c & f in Limpus & Chaloupka
(1997), which according to the figure legend are "expected size-at- age functions" obtained by numerically integrating "size-specific growth rate
functions derived using cubic B-spline fit to GAM predicted values".

I was able to fit the cubic-B spline, but I do not know how to "numerically
integrate" it.

You need to give us the function and the appropriate limits of integration.

Maybe it is even easier than I thought. Assuming your interest lies with the last fitted line ... the one on the third page ... you could perhaps just see how successful this strategy would be:

# Presumably you have already done:
# requite(mgcv)

Int.fit <- seq(100, 600, by=0.1)*predict(bspline3,
newdata=data.frame(size=seq(100, 600, by=0.1) ) )

You would need to do a sensibility check by comparing the result to a back of the envelope estimate: say 55*500=27500 . I'm a bit concerned that a dimensional analysis suggest this is an estimate of mm^2/yr, although I suppose a yearly surface area increase could be a meaningful value in some domain or another



Can anybody help please?

Code and figures here:
https://docs.google.com/fileview?id=0B1cQ7z9xYFl2ZTZhMmMyMjAtYTA3Zi00N2QyLTkxNzMtOGYyMjdiOGU2ZWE4&hl=en

Thank you,
Claudia
--

David Winsemius, MD
West Hartford, CT

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David Winsemius, MD
West Hartford, CT

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