[R] Probit Analysis: Confidence Interval for the LD50 using Fieller's and Heterogeneity (UNCLASSIFIED)

Kenney, Colleen T CTR USA AMC colleen.t.kenney at us.army.mil
Mon Nov 22 20:24:50 CET 2010

Classification:  UNCLASSIFIED 
Caveats: NONE

A similar question has been posted in the past but never answered.  My
question is this: for probit analysis, how do you program a 95%
confidence interval for the LD50 (or LC50, ec50, etc.), including a
heterogeneity factor as written about in "Probit Analysis" by
Finney(1971)?  The heterogeneity factor comes into play through the
chi-squared test for homogeneity and is equal to h=chi^2/(k-2), where k
is the number of doses and k-2 are the degrees of freedom.

I have done a lot of research on this and really appreciate any help
anyone can provide.  Thank you!

Classification:  UNCLASSIFIED 
Caveats: NONE

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