[R] model fine, predict gives an error

From: Antje Niederlein <niederlein-rstat_at_yahoo.de>
Date: Tue, 15 Mar 2011 14:15:16 +0100


Hi there,

I try to model some dose response curves (drc-package). In most cases it is fine but now I got some data which produces me the following error:

load("drmData.RData")
library(drc)

drmObj <- drm(value ~ concentration, cmpd_respvar, data = drmData, fct = LL.4()) predict(drmObj)

>> Error in chol.default(0.99 * object$fit$hessian + 0.01 * diag(dim(object$fit$hessian)[1])) :
  the leading minor of order 2 is not positive definite Error in resultMat[, 2] <- estSE : replacement has length zero

Can anybody explain to me why the calculation of the dose response model works but the prediction fails? Anything I can do in this case?

Antje



R-help_at_r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Tue 15 Mar 2011 - 13:18:57 GMT

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.2.0, at Wed 16 Mar 2011 - 08:30:21 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help. Please read the posting guide before posting to the list.

list of date sections of archive