[R] betareg help

[Achim Zeileis]

On Sat, 12 Mar 2011, Vlatka Matkovic Puljic wrote:

> Dear R users,
>
> I'm trying to do betareg on my dataset.
> Dependent variable is not normally distributed and is proportion (of condom
> use (0,1)).
> But I'm having problems:
>
> gyl<-betareg(cond ~ alcoh + drug, data=results)
> Error in optim(par = start, fn = loglikfun, gr = gradfun, method = method, :
>
> initial value in 'vmmin' is not finite
>
> Why is R returning me error in optim()?

Hard to say with the information you provide...

> What should I do?

You can try to do the usual things when numerically optimizing nonlinear 
models: (1) Check whether the data is degenerate in some way, e.g., not 
enough variation in the response for combinations of the predictors.
(2) Check whether the scaling of your regressors is ok. Maybe 
standardizing them to a numerically more stable scale is useful.
(3) Provide better starting values than the defaults.

hth,
Z

> In advance, thank you for advice!
>
>
>
>
> -- 
> **************************
> Vlatka Matkovic Puljic
> +32/ 485/ 453340
>
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