Dear Colleagues,
I am trying to do weighted nls. I have searched the archives and the white
book. I tried TBS without success. The data frame and nls invocation are below.
# cs expo fit
csdata<-data.frame(
time=c(0,1,3,9,20),
resp=c(638.697,395.69,199.00,141.58,112.16)
)
# perform nlr
cs.nls<-nls(resp~A1*exp(-a1*time)+A2*exp(-a2*time),
data=csdata,
start=list(A1=700,a1=1,A2=100,a2=0.1)
)
cs.nls
I need constant coefficient of variation =5% weighting. How do I implement this?
I will summarize and post responses.
Kind Regards,
Oscar A Linares
Molecular Medicine Unit
The University of Michigan Geriatrics Center
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