[R] ED50 calculation in drc package

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

Re: [R] ED50 calculation in drc package

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,