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2004 Jul 28
0
Modelling compound logistic growth curves
...b/) that allows one to decompose growth
curves into a series of logistic equations, I attempted to do the same thing
in R.
SIMULATED DATA
Time <- 1:200
pop.size <- SSlogis(Time,10,20,5) + SSlogis(Time,20,100,20) +
rnorm(length(Time))
MY ANALYSIS
results <- nls(size ~ SSlogis(Time, Asym1, xmid1, scal1) + SSlogis(Time,
Asym2, xmid2, scal2),
start = list(Asym1=5, xmid1=15, scal1=30, Asym2=25, xmid2=67, scal2=25))
THE RESULT
I get the error message:
Error in nls(size ~ SSlogis(Time, Asym1, xmid1, scal1) + SSlogis(Time, :
step factor 0.000488281 reduced below `minFactor' of 0.00...
2004 Aug 16
0
Multiple logistic curves
...ition of growth
curves into a series of logistic equations, I attempted to do the same thing
in R.
#SIMULATED DATA
Time <- 1:200
pop.size <- SSlogis(Time,10,20,5) + SSlogis(Time,20,100,20) +
rnorm(length(Time))
ts.plot(pop.size)
#MY ANALYSIS
results <- nls(pop.size ~ SSlogis(Time, Asym1, xmid1, scal1) + SSlogis(Time,
Asym2, xmid2, scal2),
start = list(Asym1=5, xmid1=15, scal1=30, Asym2=25, xmid2=60, scal2=25))
THE RESULT
I get the error message:
Error in nls(size ~ SSlogis(Time, Asym1, xmid1, scal1) + SSlogis(Time, :
step factor 0.000488281 reduced below `minFactor' of 0.00...