Thank you Keo! After installing MASS the default "psi=psi.huber" is working now. However I still can't get "psi=psi.bisquare" to work, and here's another error message: > model3=nlrob(y~a1*x^a2,data=transient,psi=psi.bisquare, > start=list(a1=0.02,a2=0.7),maxit=1000) Error in na.fail.default(list(y = c(71.2600034232749, 148.175742933206, : missing values in object
I don't know why there are missing values, I'm sure y is the right length and there are no NAs in it. Could somebody help me with this one please? Thanks in advance, Xiao On Wed, Aug 12, 2009 at 11:47 PM, Keo Ormsby<christopher.orm...@cieni.org.mx> wrote: > You have to install MASS package first. > Hope this does the trick. > Best, > Keo. > > Xiao Xiao wrote: >> >> Hi all, >> >> I'm trying to fit a nonlinear regression by "nlrob": >> >> model3=nlrob(y~a1*x^a2,data=transient,psi=psi.bisquare, >> start=list(a1=0.02,a2=0.7),maxit=1000) >> >> However an error message keeps popping up saying that the function >> psi.bisquare doesn't exist. >> >> I also tried psi.huber, which is supposed to be the default for nlrob: >> >> model3=nlrob(y~a1*x^a2,data=transient,psi=psi.huber, >> start=list(a1=0.02,a2=0.7),maxit=1000) >> >> But I still got the same error message - psi.huber doesn't exist. >> >> Is the argument "psi" not available in nlrob? >> >> Any help will be appreciated. >> >> Best, >> Xiao Xiao >> >> ______________________________________________ >> R-help@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide >> http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. >> > > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
