Tag Archives: Growth

“Vignettes” Update

As a follow-up to my post about major changes to FSA and that some of the “old” vignettes are now out-of-date, here is a brief summary of new material in the draft book chapters (linked to below) that replaced the … Continue reading

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Weisberg Growth Model

A fishR user asked me if I had Weisberg Linear Growth Model (LGM) vignette.  In the past, the Weisberg LGM referred to the fixed-effects models described in Weisberg (1993) and implemented in software that was written in XLISP-STAT and distributed … Continue reading

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Comparison Among Groups with Francis Parameterization

In my last post, I suggested that the Francis parameterization of the von Bertalanffy growth model may be used in cases where the typical parameterization did not converge (likely due to issues related to highly correlated parameters and data with … Continue reading

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A Problem Fitting the von Bertalanffy Growth Model with nls()

Recently, a fishR user asked me the following (modified) question: I have successfully fit the typical von Bertalanffy growth model to all of my fish. However, when I subset the data by sex and attempt to fit the model separately … Continue reading

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Francis Parameterization in FSA

I just made some changes to vbFuns() and vbStarts() in the FSA v0.4.2 package.  Specifically, I changed the requirement for providing three ages (t1, t2, and t3) arguments for the functions related to the Francis parameterization to only providing two … Continue reading

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An FSA Reference

The FSA package was recently referenced in “Validated age, growth and reproductive biology of Carcharhinus melanopterus, a widely distributed and exploited reef shark” published in Marine and Freshwater Research 64:985-975.  The authors used the package for age bias and precision calculations and for … Continue reading

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R-Squared for a VBGM

Recently, a fishR user asked me the following question: After fitting the age-length data into VBGM, I overviewed the results. But I can’t find the coefficient of determination () for the VBGM fitting. Because some reviewer want the the coefficient … Continue reading

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Updated FSA

Today I posted FSA version 0.2-0 to rforge.net.  This is a moderately major change form previous versions in that most of the function names have been changed to camel-case — i.e., growthModelsSim() instead of growth.models.sim().  As I have not “officially” … Continue reading

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More AIFFD Examples

I have uploaded examples for most of Chapter 5 in the Analysis and Interpretation of Freshwater Fisheries Data. Some of the examples are, as of yet, somewhat incomplete or will be modified in the future as I had several questions … Continue reading

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Modifications to von Bertalanffy General Example

I have modified the von Bertalanffy general example by making some minor grammatical corrections, including a description of the parameterization proposed by Francis (1988), and including a brief description of Fabens’ method for tag-recapture data. The modification is found under … Continue reading

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