(a) This is pretty obviously homework; the r-help list is *not* for
giving help with homework.
(b) *Read* the error message!
(c) Your expression for the log likelihood is wrong in more than
one way. (The number of observations is *not* the same thing
as the number of trials for a given observation.)
cheers,
Rolf Turner
On 27/09/11 15:33, jango wrote:
I'm trying to calculate the maximum likelihood estimate for a binomial
distribution. Here is my code:
y<- c(2, 4, 2, 4, 5, 3)
n<- length(y)
binomial.ll<- function (pi, y, n) { ## define log-likelihood
output<- y*log(pi)+(n-y)*(log(1-pi))
return(output)
}
binomial.mle<- optim(0.01, ## starting value
binomial.ll, ## log likelihood
method="BFGS", ## optimization method
hessian=TRUE, ## numerial Hessian
control=list(fnscale=-1), ## max, not min
y=y, n=n)
binomial.mle.par<- c(binomial.mle$par, -1/binomial.mle$hessian[1,1])
binomial.mle.par<- as.matrix(binomial.mle.par)
rownames(binomial.mle.par)<- c("lambda", "s.e.")
colnames(binomial.mle.par)<- c("MLE")
print(binomial.mle.par)
When I do this I get the following error message:
Error in optim(0.01, binomial.ll, method = "BFGS", hessian = TRUE, control =
list(fnscale = -1), :
objective function in optim evaluates to length 6 not 1
Any help you can give me would be greatly appreciated.
--
View this message in context:
http://r.789695.n4.nabble.com/Error-in-optim-function-tp3846001p3846001.html
Sent from the R help mailing list archive at Nabble.com.
______________________________________________
R-help@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.
______________________________________________
R-help@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.
