[R] dose.p in MASS
ripley at stats.ox.ac.uk
Tue Jul 16 15:48:19 CEST 2002
On Tue, 16 Jul 2002, Smit, A, Albertus, Dr wrote:
> Dear all
> I need to obtain an estimate of the 50% lethal dose (LD50) from a
> logistic regression model obtained by applying the glm procedure to
> some binomial data. The model appears to fit the data very well. I
> used dope.p from MASS to try and find LD50.
> The following output appears:
> > dose.p(iso.glm.logit, cf = c(1,3), p = 1:3/4)
> Error in dose.p(iso.glm.logit, cf = c(1, 3), p = 1:3/4) :
> subscript out of bounds
> What is the problem here? The error disappears when fiddle around
> with cf (e.g., cf = c(1,2)), but I have no idea what this does, or even
> what the cf parameter is used for.
There is a help page for dose.p(), and it does explain the argument `cf'!
Probably the default cf=1:2 is what you want, but without seeing how you
created iso.glm.logit we can only guess.
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272860 (secr)
Oxford OX1 3TG, UK Fax: +44 1865 272595
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch
More information about the R-help