Hi,
I've just been programming a function to calculate the likelihood in a
probit model.
The function looks like this
likelihood <- function(Y,X,p) {
Z <- p[1] +p[2]*X
P <- Y*pnorm(Z) + (1-Y)*(1-pnorm(Z))
-prod(P)
}
out <- optim(likelihood,p=c(0,0),Y=wells$switch,X=wells$dist, hessian=TRUE)
X and Y are vectors containing column data.
This works fine, however, if I rename p to pp or anything that is longer
than one character, I get the following error message:
Error in optim(f, pp = c(0, 0), Y=wells$switch, X=wells$dist,
hessian=TRUE) :
cannot coerce type closure to double vector
This seems like a bug... Or can you help me find the mistake I made?
Thanks,
Christa
--
Christa Deiwiks
International Conflict Research
ETH Zurich
Seilergraben 49 (SEI E.3)
8092 Zurich
Ph: +41 44 632 67 60
http://www.icr.ethz.ch/people/deiwiks
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