Let do a simple glm:

> y=rnorm(100)
> gnul <- glm(y ~ 1)
> gnul$coefficients
(Intercept)
  0.1399966

The logLik shows the fit of two parameters (DF=2) (intercept) and sd

> logLik(gnul)
'log Lik.' -138.7902 (df=2)

But where is the sd term in the glm object?

If I do the same with optim, I can have its value

> dnormx <- function(x, data) {1E9*-sum(dnorm(data, mean=x["mean"], sd=x["sd"], log = TRUE))}
> parg <- c(mean=0, sd=1)
> o0 <- optim(par = parg, fn=dnormx, data=y, method="BFGS")
> o0$value/1E9
[1] 138.7902
> o0$par
     mean        sd

0.1399966 0.9694405

But I would like have the value in the glm.

(and in the meantime, I don't understand why gnul$df.residual returned 99... for me it should be 98=100 - number of observations) -1 (for mean) - 1 (for sd); but it is statistical question... I have asked it in crossvalidated [no answer still] !)

Thanks

Marc

______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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.

Reply via email to