Hi, Thanks for all the answers. Think with your help I got it now. It was apparently a typical newbie question. I'll try omitting NAs globally in this case.
Thanks, Christian ______________________________________________ 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.
