Thank you, gentlemen. I greatly appreciate your help.
-- Michal J. Figurski, PhD HUP, Pathology & Laboratory Medicine Biomarker Research Laboratory 3400 Spruce St. 7 Maloney Philadelphia, PA 19104 tel. (215) 662-3413 ______________________________________________ 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.