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cohort
2012 Sep 10
0
More help need on Von Bertalanffy Growth Curves
...(nlstools)
# provide starting values
svCom <- list(Linf=199.8132, K=0.5631745, t0=-1.960147)
svCom <- vbStarts(Length~Age,data=BLG)
# repeat the starting values for each Cohort
svGen <- lapply(svCom, rep, length(unique(Cohort)))
# define a new variable, uniquely numbered for each Cohort
Cohortf <- as.factor(Cohort)
# fit a single model with different parameter estimates for each Cohort
vbGen <- Length~Linf[Cohortf]*(1-exp(-K[Cohortf]*(Age-t0[Cohortf])))
fitGen <- nls(vbGen,data=BLG,start=svGen)
#fit a single model with the same parameter estimates using all the Cohorts data#
vb...