[R] ZINB by Newton Raphson??

[Achim Zeileis]

On Mon, 21 Jun 2010, cahyo kristiono wrote:

> Dear all..
> I have a respon variable y. Predictor variable are x1, x2, x3, x4, x5
> (1)?What is?the syntax to get paramater estimation of?ZINB Model by 
> Newton Raphson (not BFGS)

I guess you are talking about the function zeroinfl() from the package 
"pscl"? It supports all "method"s of optim() and in addition supports "EM" 
estimation. Typically, all yield very similar optimized likelihood values 
and associated parameters.

> (2) What syntax to plot probability of observed & predicted of ZINB

That depends on what type of predictions you want to obtain. The vignette
   vignette("countreg", package = "pscl")
has some examples and further explanations.

Best,
Z

> Thx.
> Regards
> Krist.
>
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