My data consist of two columns: time and cumulative number like below:
time <- c(1:14)
cum.num <- c(20, 45, 99, 195, 301, 407, 501, 582, 679, 753, 790, 861, 1011, 1441)
My non linear function is:
c1*cos(0.6731984259*time)+c2*sin(0.6731984259*time)+c3*(time)^2+c4*time+c5
My objective is to model this function using non linear regression using nls() in R and to compute the confidence interval. I have donr the following:
m1.fit<-nls(cum.vul~c1*cos(0.6731984259*time)+c2*sin(0.6731984259*time)+c3*(time)^2+c4*time+c5,start=list(c1=-50,c2=-60,c3=5,c4=8,c5=100))
I got an error while computing confidence interval, i have tried the following:
confint(m1.fit)
Once i issued this command got the following error:
Waiting for profiling to be done... Error in prof$getProfile() : step factor 0.000488281 reduced below 'minFactor' of 0.000976562
Can anyone help me in this regard?
Try package nlstools:
> nlstools::confint2(m1.fit)
2.5 % 97.5 %
c1 -48.556270 54.959689
c2 -175.654079 -45.216965
c3 3.285062 9.529072
c4 -49.254627 46.007629
c5 -34.135835 272.864743`