emorway wrote: > > > So I wanted to try a different equation of the general form a/(b+c*x^d) > > US.nls.2<-nls(US.final.values$ECe~(a/(b+c*US.final.values$WTD^d)),data=US.final.values,start=list(a=100.81,b=73.7299,c=0.0565,d=-6.043),trace=TRUE,algorithm="port") > > but that ended with "Convergence failure: false convergence (8)". I tried > relaxing the convergence > >
You want 4 parameters from a set of data that has a very large variance. Try to fix d and c to a reasonable constant; it probably will converge. >From looking at your data and the variances, I would suggest to log-transform first. If you feel bad about it, you can always fit the original data later after you have found a good model. Dieter -- View this message in context: http://n4.nabble.com/different-forms-of-nls-recommendations-tp1676330p1676547.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.
