[R] ED50 calculation in drc package

[Bert Gunter]

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 <ldiao at 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
>
>
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>
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-- 

Bert Gunter
Genentech Nonclinical Biostatistics

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