This data are kilojoules of energy that are consumed in starving fish over a
time period (Days). The KJ reach a lower asymptote and level off and I
would like to use a non-linear plot to show this leveling off. The data are
noisy and the sample sizes not the largest. I have tried selfstarting
weibull curves and tried the following, both end with errors.
Days<-c(12, 12, 12, 12, 22, 22, 22, 22, 32, 32, 32, 32, 37, 38, 38, 39, 39,
39, 39, 39, 39, 39, 1, 1, 1, 1)
Joules<-c(8.782010, 8.540524, 8.507526, 11.296904, 4.232690, 13.026588,
10.213342, 4.771482, 4.560359, 6.146684, 9.651727, 8.064329, 9.419335,
7.129264, 6.079012, 7.095888, 17.996794, 7.028287, 8.028352, 5.497564,
11.607090, 9.987215, 11.065307, 21.433094, 20.366385, 22.475717)
X11()
par(cex=1.6)
plot(Joules~Days,xlab="Days after fasting was initiated",ylab="Mean energy
per fish (KJ)")
model<-nls(joules~a+b*exp(-c*Days),start=list(a=8,b=9,c=-.229),
control=list(minFactor=1e-12),trace=TRUE)
summary(model)
init <- nls(Joules~ SSweibull(Days,Asym,Drop,lrc,pwr),
control=list(minFactor=1e-12),data=.GlobalEnv)
init
Data here is reproducible.
As always, thank you...keith
--
M. Keith Cox, Ph.D.
Alaska NOAA Fisheries, National Marine Fisheries Service
Auke Bay Laboratories
17109 Pt. Lena Loop Rd.
Juneau, AK 99801
keith....@noaa.gov
marlink...@gmail.com
U.S. (907) 789-6603
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