Lixia: This is not fundamentally an R issue. You seem to have some confusion about what IC50's and ED50's are in the statistical modeling context. I suggest you consult one of the fine statisticians at MD Anderson to help you resolve your confusion.
Cheers, Bert On Tue, Jan 3, 2012 at 10:11 AM, Diao,Lixia <ld...@mdanderson.org> wrote: > Hi, > > I am trying to use drc package to calculate IC50 value. The ED50 calculated > in some models (LL4 for example) as a response half-way between the upper and > lower limit, which is the definition of the relative IC50 value. Does that > mean the ED50 in drc package is IC50? How the ED function in drc package > distinguish to estimate ED or IC values? > > Thanks a lot > > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm ______________________________________________ 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.
