[R] Error fitting ZIP with zeroinfl()

[Achim Zeileis]

On Thu, 11 Dec 2008, Paige Barlow wrote:

> I am attempting to fit a full zero-inflated Poisson model then use backward 
> elimination to arrive at the best-fitting model.  When I try to fit the model 
> with zeroinfl() I get this error:
>
> Error in while (abs((ll_old - ll_new)/ll_old) > control$reltol) { :
>       missing value where TRUE/FALSE needed
>
> Any suggestions?

Read the posting guide linked at the end of the mail. The information 
above is really insufficient to say much useful.

The error message suggests that something in the specification of starting 
values is not correct. You seem to have used EM = TRUE, try (the default) 
EM = FALSE instead.
Z

> Thanks for your help!
>
> Paige Barlow
> MS Student
> Virginia Tech
> Dept Fish and Wildlife
>
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>