Re: st: probit modeling

[James Valcour <jvalcour@rogers.com>]

Hi Kristy,

I have an ado file that performs probit analysis that had written for a 
grad student at my old job.  They were doing bioassays for their project 
and needed similar information.  It was tailored to their specific needs to 
make life as easy as possible them.

If you could let me know how your data is set up (i.e. is it collapse into 
a table for, or is it one line for every subject in the dataset) I could 
easily adapt this program to suit your needs.  It performs a probit 
analysis and displays the LD50 and associated Feiller confidence 
limits.  It will also account for natural mortality it that occurs.

James Valcour

At 1/14/03 04:34 PM -0800, you wrote:


> Hello,
>
> Can anyone suggest a reference for how to calculate the confidence limits 
> of an LD50 (i.e. 50% lethal dose level) obtained from a probit model?  The 
> data is from a drug toxicity experiment in mice.  I've figured out how to 
> derive the LD50s from the model parameter estimates, but I'm stuck on how 
> to calculate the variance of the LD50 estimate.
>
> Thanks,
>
> Kristy
> ------------------------------------------------------------------------
> Kristy Seidel
> Clinical Research Center/Research Administration
> Children's Hospital and Regional Medical Center,  Seattle WA
> kristy.seidel@seattlechildrens.org
> -------------------------------------------------------------------------

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